Integrating ground cover crops and new herbicide strategies, conventional and organic, for tree growth and soil health-part II

Final Report for ONE12-156

Project Type: Partnership
Funds awarded in 2012: $14,995.00
Projected End Date: 12/31/2013
Region: Northeast
State: New York
Project Leader:
Deborah Breth
Cornell Cooperative Extension
Expand All

Project Information

Summary:
Ground cover seeding options

This project showed that fall or spring planting was more effective than early summer for establishing grass ground cover between orchard rows. We evaluated a new ground cover option “Low-Grow mix”, a low growing, low maintenance mixture of four fescue seeds compared to OVN at 2 seeding rates and Dutch white clover. In 2012, six GC treatments were seeded early spring at Fowler Farms and utilized lower rates (16 and 22 lbs/acre) for both grass mixtures. There were no consistent benefits of using the new low maintenance mixture of fescue seeds (Low-Grow mix, either using the low or high rates) over two years of continuous observation. Evaluation of weed coverage (%), ground cover coverage (%), and ground cover height (inches) in year 2 and at the beginning of year 3 determined that the Low-Grow Mix is not yet a better replacement to the widely used OVN-Mix. The OVN-mix is still a good grass ground cover alternative and one of the cheapest options if planted early in the spring or late in the summer (August 15-Sept.15) in Northeastern apple fruit regions. Clover was easy to establish. But the disadvantages of using clover include 1) the invasion of clover in the tree rows, 2) herbicides are generally ineffective against clover, 3) clover flowers in the summer will be a problem when growers need to apply insecticides or carbaryl at petal fall for thinning which will affect pollinators.

Herbicide treatments

This project supported the side-by-side demonstration and testing of new herbicide options in new, high density apple plantings compared to some old standard herbicides. No herbicide program in these plots gave season long control. But there were differences in the number of post-emergent herbicide applications required depending on the residual herbicide used in the spring. Irrigation definitely reduces the residual herbicide effect and requires more post-emergence treatments. To evaluate any negative impact of the use of glyphosate in these plantings, 2 treatments used glyphosate for post-emergent control with residual herbicides. No trunk damage was noted in glyphosate treated plots. We compared the resulting tree growth and determined the best treatment for weed control resulted in trunk size twice that in the weedy check. The weed species and growth cycles of the weed populations showed the untreated weedy check plots clearly had the greatest percent weed cover by perennial weeds, and the greatest number of perennial weed species after 2 seasons. A preliminary study of the resulting soil health measurements showed that a hardpan at 9 inches deep is common in orchards. This project showed that weed control is critical to tree growth and ultimate profitability of new plantings in the early years. Weed control impacts on how soon the orchard will reach a breakeven point using Net Present Value Analysis. Good weed control can improve profitability of a new high-density apple planting by $2105-2732 per acre over 2 seasons.

Introduction:

Partner Farms

The growers partnering in this project were Lamont Fruit Farm and Mason Farms. Lamont Fruit Farm is a 480 acre farm producing 85% fresh market apples; the remainder go to the processing market. They have been in the forefront of developing and implementing new technology in fruit production from high density planting systems of 2000 trees per acre, to minimizing pesticide use through sprayer innovations, and growing nursery trees for the farm. They have been relying on a post-emergent weed control program of glyphosate and 2,4-D for the past 10 years and are concerned over the potential for glyphosate resistant weeds and the long term sustainability of this program. They would like to explore new alternative weed management options. They would like to explore different cover crops for traffic durability, efficient water usage, water penetration and nutrient management. Mason farms is a 7th generation family farm operating over 200 years in Williamson, NY. They grow 500 acres of vegetables, 200 acres of tree fruit, and 60 acres of organic leafy greens and other vegetables. They are an Integrated Pest management and Certified Organic operation.

Ground cover seeding options

Grasses are the most common cover crops in apple orchards in Western NY. Many different grasses and grass mixtures are available. The OVN-Mix is the most common cover crop mix seeded after an apple orchard is planted today. Ideally, preparation for ground-cover establishment should begin at the same time as preparations for orchard establishment. Once the trees are planted, posts and wires should be installed quickly to support tree growth, followed by ground cover seeding and rolling. The entire sequence of orchard tasks (tree planting, post and wire installation, and ground cover seeding) should be conducted the first 4-5 weeks after planting. Trickle irrigation system should also be installed soon after planting. A cover crop should germinate quickly, establish itself quickly, and thereafter should not require much maintenance (fertilization or chemical weed control). It also has to be resilient under heavy traffic (especially at the bottom of more steep slopes) for insect and disease spray equipment. A good ground cover establishment must be achieved with an optimal and economical seeding rate and must be maintained with minimal extra effort by the grower. It should be chosen and managed so that competition for nutrients and water with apple trees is minimal.

Grass ground covers will require mowing several times each year (4-6 times per year). A mowing height of 3-5 inches is best. Mowing before or during harvest will facilitate moving ladders, platforms, sprayers, hedgers, tractors, and bins through the orchard. High density apple orchards should be mowed after harvest or late in the fall to remove habitat favorable for rodents. A ground cover that help maintain soil structure, encourage water infiltration, reduce soil erosion, reduce mud, secure and maintain a good driving surface, and doesn’t need to be mowed so often (because a high density and modern apple orchard as the Tall Spindle has several row middles to mow per season!), are ideal characteristics for a fruit grower looking to minimize high fuel costs, time, and labor.

Ground cover seeding options

Grasses are the most common cover crops in apple orchards in Western NY. Many different grasses and grass mixtures are available. The OVN-Mix is the most common cover crop mix seeded after an apple orchard is planted today. Ideally, preparation for ground-cover establishment should begin at the same time as preparations for orchard establishment. Once the trees are planted, posts and wires should be installed quickly to support tree growth, followed by ground cover seeding and rolling. The entire sequence of orchard tasks (tree planting, post and wire installation, and ground cover seeding) should be conducted the first 4-5 weeks after planting. Trickle irrigation system should also be installed soon after planting. A cover crop should germinate quickly, establish itself quickly, and thereafter should not require much maintenance (fertilization or chemical weed control). It also has to be resilient under heavy traffic (especially at the bottom of more steep slopes) for insect and disease spray equipment. A good ground cover establishment must be achieved with an optimal and economical seeding rate and must be maintained with minimal extra effort by the grower. It should be chosen and managed so that competition for nutrients and water with apple trees is minimal.

Grass ground covers will require mowing several times each year (4-6 times per year). A mowing height of 3-5 inches is best. Mowing before or during harvest will facilitate moving ladders, platforms, sprayers, hedgers, tractors, and bins through the orchard. High density apple orchards should be mowed after harvest or late in the fall to remove habitat favorable for rodents. A ground cover that help maintain soil structure, encourage water infiltration, reduce soil erosion, reduce mud, secure and maintain a good driving surface, and doesn’t need to be mowed so often (because a high density and modern apple orchard as the Tall Spindle has several row middles to mow per season!), are ideal characteristics for a fruit grower looking to minimize high fuel costs, time, and labor.

Ground cover seeding options

Grasses are the most common cover crops in apple orchards in Western NY. Many different grasses and grass mixtures are available. The OVN-Mix is the most common cover crop mix seeded after an apple orchard is planted today. Ideally, preparation for ground-cover establishment should begin at the same time as preparations for orchard establishment. Once the trees are planted, posts and wires should be installed quickly to support tree growth, followed by ground cover seeding and rolling. The entire sequence of orchard tasks (tree planting, post and wire installation, and ground cover seeding) should be conducted the first 4-5 weeks after planting. Trickle irrigation system should also be installed soon after planting. A cover crop should germinate quickly, establish itself quickly, and thereafter should not require much maintenance (fertilization or chemical weed control). It also has to be resilient under heavy traffic (especially at the bottom of more steep slopes) for insect and disease spray equipment. A good ground cover establishment must be achieved with an optimal and economical seeding rate and must be maintained with minimal extra effort by the grower. It should be chosen and managed so that competition for nutrients and water with apple trees is minimal.

Grass ground covers will require mowing several times each year (4-6 times per year). A mowing height of 3-5 inches is best. Mowing before or during harvest will facilitate moving ladders, platforms, sprayers, hedgers, tractors, and bins through the orchard. High density apple orchards should be mowed after harvest or late in the fall to remove habitat favorable for rodents. A ground cover that help maintain soil structure, encourage water infiltration, reduce soil erosion, reduce mud, secure and maintain a good driving surface, and doesn’t need to be mowed so often (because a high density and modern apple orchard as the Tall Spindle has several row middles to mow per season!), are ideal characteristics for a fruit grower looking to minimize high fuel costs, time, and labor.

Ground cover seeding options

Grasses are the most common cover crops in apple orchards in Western NY. Many different grasses and grass mixtures are available. The OVN-Mix is the most common cover crop mix seeded after an apple orchard is planted today. Ideally, preparation for ground-cover establishment should begin at the same time as preparations for orchard establishment. Once the trees are planted, posts and wires should be installed quickly to support tree growth, followed by ground cover seeding and rolling. The entire sequence of orchard tasks (tree planting, post and wire installation, and ground cover seeding) should be conducted the first 4-5 weeks after planting. Trickle irrigation system should also be installed soon after planting. A cover crop should germinate quickly, establish itself quickly, and thereafter should not require much maintenance (fertilization or chemical weed control). It also has to be resilient under heavy traffic (especially at the bottom of more steep slopes) for insect and disease spray equipment. A good ground cover establishment must be achieved with an optimal and economical seeding rate and must be maintained with minimal extra effort by the grower. It should be chosen and managed so that competition for nutrients and water with apple trees is minimal.

Grass ground covers will require mowing several times each year (4-6 times per year). A mowing height of 3-5 inches is best. Mowing before or during harvest will facilitate moving ladders, platforms, sprayers, hedgers, tractors, and bins through the orchard. High density apple orchards should be mowed after harvest or late in the fall to remove habitat favorable for rodents. A ground cover that help maintain soil structure, encourage water infiltration, reduce soil erosion, reduce mud, secure and maintain a good driving surface, and doesn’t need to be mowed so often (because a high density and modern apple orchard as the Tall Spindle has several row middles to mow per season!), are ideal characteristics for a fruit grower looking to minimize high fuel costs, time, and labor.

Herbicide treatments

Weed control in new orchards has been treated the same for the last 20 years even though our planting systems of apples has changed significantly. Tree density has increased from 217 trees per acre to 1200 tree per acre using M9 clone or Bud 9 rootstocks. It costs approximately $10,000 per acre to establish a new orchard and growers plan to pick a crop in the second leaf to start to recoup their investment. Research done by Ian Merwin in 1986-1997 showed that 1) pre-emergent herbicides and tilled treatments decreased soil organic matter, 2) pre-emergent herbicide treatments reduced water infiltration rates, 3) grass and vetch ground covers lowered free N supply, 4) the lowest yields were in grass or vetch plots but improved fruit color and firmness, 5) there was no difference in yield between 1.5 vs. 2.5 m herbicide strip, 6) mulch treatments (except for bark mulch) result in tree death from Phytophthora and voles, and 7) there is more erosion/water runoff potential in pre- and post-emergent herbicide treated plots. Merwin concluded that the critical weed free timing was between May through July. Merwin showed that minimizing weed competition under the trees will impact tree growth, irrigation scheduling, orchard nutrition, vole control, soil health factors, general tree health, and ultimate profitability of lower density orchards. This work was done using Empire on M111 and Gala on M26.

Since that time several new herbicide options, both pre-emergent and post-emergent, have been registered for use and few researchers in the country remain to do weed management studies in orchards. There are new concerns over the use of glyphosate in resulting in winter damage and trunk injury by affecting the Shikimic acid pathway and the development of resistance to glyphosate in several weed species. There is also resistance noted to simazine (triazines) indicating the need to rotate herbicide chemistry. And if no glyphosate is used there is a tendency for orchards to develop a population of perennial weeds that are difficult to control.

Project Objectives:
  • Identify the pros and cons of various ground cover seeding options.
    Identify strengths and weaknesses in side-by-side herbicide treatments.
    Evaluate control of established perennials.
    Evaluate herbicide treatments for trunk damage from glyphosate.
    Evaluate changes in soil health.

Cooperators

Click linked name(s) to expand
  • Roderick Farrow
  • J. D. Fowler
  • Douglas Mason
  • Mario Miranda Sazo

Research

Materials and methods:
Ground cover

From the 2011 SARE Partnership grant, ONE11-138, Ground Cover (GC) Plantings:
Two ground cover trials were partially established in 2011. The Mason GC and the Lamont GC trials were seeded on June 9 and August 15, respectively. At both sites, three replications of six ground covers treatments (Table 1) were seeded (hand-broadcasted at Mason and mechanically seeded with a brillion at Lamont), maintained, and mowed when needed by grower cooperators. The Mason GC trial was mowed on August 4, 22, Sept.28, and Nov 15. The Lamont GC trial was mowed only one time at the end of the growing season on Nov. 18. Percentage cover of sod row middles and weed composition were evaluated on August 22 at the Mason GC site and on Sept. 30 and October 6 at the Lamont GC site.

Current grant: 2012 Ground Cover (GC) Plantings: The Mason GC site failed to establish and was not terminated in 2011. All same plots were reseeded with an oat nurse crop on March 16, 2012. A third GC site (called “GC Fowler trial”) was established early in the spring of 2012 to collect missed information from the Mason site in 2012 (Table 2). The Mason GC site was evaluated on May 21, 2013.

In May 1st 2012, the GC Fowler trial was established using a Super Spindle high density orchard (2’x10’) of Fuji and Gala on M.9 rootstock with grower cooperator JD Fowler in Wolcott, NY. The apple orchard was planted in the fall of 2011. The GC Fowler trial compared side-by-side both ground cover mixes (OVN-mix and Low-Grow mix) and two seeding rates (16 and 22 lbs/acre). GC mixes were seeded with a brillion seeder and immediately rolled on May 2, 2012. The following GC management systems were studied: Trt1 (untreated-natural vegetation), Trt 2 (OVN-mix 16lbs/acre), Trt 3 (Low-Grow mix 16lb/acre), Trt 4 (OVN-mix 22lbs/acre), Trt 5 (Low-Grow mix 22 lbs/acre), and Trt 6 (Dutch clover at 16lbs/acre). Ground covers were well established, maintained, and mowed when needed by grower cooperator. Soil coverage (GC coverage, weed coverage, and GC height) was monitored in 2012 and 2013 seasons.

Herbicide treatments

Herbicide treatments were applied with a CO2 R & D sprayer using 2 L bottles for each treatment using a single Spraying Systems 8004 110o EVS nozzle, .28 gallons per minute at 30 psi, at 2 mph. Herbicide strips in rows at Lamont’s and Mason’s were 3 ft wide. Treatments were randomized and replicated, 3 replicates per treatment, in each of 2 sites. In the Lamont Fruit Farm site, there were a total of 15 treatments including an untreated control. In the Mason Farms site, there were 18 treatments including an untreated control. Various herbicide treatments were applied based on label restrictions. The first treatments were applied using GoalTender and mixes that included GoalTender since the label requires application by budswell. The next treatments were applied by pink bud using Chateau in tank mixes with other herbicides including Prowl H2O or Surflan. The final set of treatments were all others without label restrictions regarding timing applied on April 19 at Lamont Fruit Farm and May 2 at Mason’s. All treatments using residual herbicides were combined with a post-emergent herbicide such as glyphosate or paraquat. This was the second season the same herbicide treatments were applied to the same plots. The treatments are all described in Table 6 and 7 for Lamont and Mason, respectively.

The percent weed cover was evaluated in each plot taking 3 readings per plot at 2-3 week intervals, and an annual average percent weed cover per treatment was calculated. When the plots reached 20-30% weed cover, they were treated again with the prescribed post-emergent herbicide – paraquat, glyphosate, or Rely. The weeds present in the plots for each date of evaluation were identified and recorded. Some of the treatments at Lamont’s had some fall treatments applied on Oct 17, 2012, including Trt 7, 9, and 12 using 2,4-D, Trt 2 using 2,4-D plus glyphosate, and Trt 11 using Rely. The data has been analyzed using General Anova with statistical difference if p <.05 and means separation by Tukey HSD.

We calculated the number of days the residual treatments were effective before any post-emergent control was necessary, and the total number of applications for the season for economic analysis.

Measurement of herbicide treatments for tree growth and trunk damage

We measured the tree trunk diameter at 30 cm above the graft union using a caliper, and calculated the trunk cross-sectional area (TCSA) in cm2. Based on crop load management research done by Robinson, et al, we calculated the potential crop production after 1 and 2 years of different herbicide programs and determined the potential difference in profitability with good vs. no weed control using the Net present Value Excel Workbook constructed by Alison DeMarree, Lake Ontario Fruit Program of Cornell Cooperative Extension.

We examined the trunks of the trees looking for any bark damage that was visible in Spring of 2013.

Measurement of changes in soil health in herbicide treatments

We collected soil health core samples for the untreated check and treatment 4, 10, 11 between the planted tree row and the edge of the herbicide strip and submitted them to the Cornell Soil Health Lab for various soil health parameters including nutrients. We also tried some Cornell water infiltration tests on the untreated check and treatment 10. Field-saturated infiltrability (ifs) reflects the steady-state infiltration capacity of the soil, after wet-up. The purpose of this data is only preliminary data collection.

Measurement of control of perennial weeds

Rod Farrow of Lamont Fruit Farms identified a new orchard site for planting in 2013. The field was planted in corn in 2012. The field was mapped using GPS with marked waypoints for weedy spots identifying persistent weeds in the field. We identified the weed control options in the corn in light of the pending apple planting to include Roundup plus 2 oz./acre of Banvel (dicamba) for perennial broadleaf weeds, followed by Roundup plus .3 oz./acre of Yukon (halosulfuron-methyl and dicamba) for control of annual broadleaf weeds and nutsedge. The field was harvested, sub-soiled, plowed and disked. The new orchard was planted in the spring of 2013. The new orchard planting was evaluated by GPS waypoints in May, 2013, with the weed map to identify the perennial weeds that survived the treatment.

We also evaluated herbicide plots at Lamont’s and Mason’s in March, 2013, after 2 years to identify perennial weeds that persisted after treatments.

Research results and discussion:
Ground cover seeding options

The 2011 year was a challenging season weather-wise. Apparently, the Mason ground cover plots were more affected by an early and severe summer drought than the Lamont ground cover plots which were not seeded manually after a severe heat hit our region. GC plots were not well established at the Mason site. Temperatures were unseasonably warm in Western NY with over 15 days at 90 degrees F or above during the June and July months.

At the Mason GC site, ground cover seeds were hand-broadcasted into plots. Plots were raked, then rolled with a packer to shallowly incorporate seed and pack the surface. Unfortunately, overall ground cover emergence did not look very good and was delayed for more than a month. Plots were not irrigated before or after the ground covers were seeded as soil moisture was adequate at planting. The first rain (0.45 inches) occurred 13 days after plots were seeded. Overall maximum temperatures for the months of June, July, August, and September, 2011 were 91 degrees F, 99.5 degrees F, 86 degrees F, and 86 degrees F, respectively. Total rain amounts for the months of June and July were lower than two inches. Rains increased and were 7.09 and 5.17 inches for August and September, respectively. By the end of August 2011, the OVN-mix and the Low-Grow mix treatments did not successfully establish, did not fill in well and were severely contaminated by summer weeds (not by fine fescues as desired). Soil coverage of fine fescues was less than five percent for both mixes.

Emergence of spring seeded ground covers was difficult to quantify early because grass identification was difficult and weed pressure (on-site grasses) was medium-high. Typically, with a few exceptions per plot, ground cover seeds did not germinate or emerged poorly without rain or irrigation. Plots were not hand weeded to identify seeded grasses. We did not see treatment differences in the ability to emerge, establish a stand, and compete with weeds in 2011 (Table 3). Next year data was not taken to help sort this out as a new site at Fowler Farms was established in March 2012. In May 2013, final measurements were taken for all treatments to give us additional information on ground cover survival at the Mason GC site. Both grass populations were sparse, did not properly establish, and did not provide adequate cover and good weed suppression. Apparently, both mixes of ground covers showed disadvantages in terms of decreased adaptation to drought conditions in 2011 and a very low capacity of recovery in 2012 and 2013. GC species at the Mason site did not establish well in year 2 and 3, and by May 21st 2013 the species mixtures has changed. GC treatments were mostly comprised of clover with a trace of rye and native grass populations. In some cases, we measured 25-95% bare ground on several plots. At Mason, the use of a brillion and a wider and heavier roller may have placed the seeds more deeply on the ground and seeds may have had more soil moisture available for germination and better establishment. Better soil preparation may have also helped to prevent this failure.

At the Lamont GC site, all ground covers grew reasonably well in 2011, 2012, and at the last evaluation date in May 2013. Overall ground cover emergence did look pretty good for all treatments 45 days after plots were seeded in 2011. Soil moisture was adequate at the moment of planting and plots did not receive supplemental irrigation. First germination was observed with the Dutch white clover seeds 9 days after plots were seeded, followed by the OVN-mix , and lastly by the Low-Grow mix. Overall maximum temperatures for the months of August, Sept., and October were 69.2 degrees F, 63.3 degrees F, and 50.8 degrees F, respectively. Two months after planting, the rain measurements were two times higher than at the Mason GC site and were 3.94 and 4.41 inches, respectively. Average air temperatures were also lower and not as severe. By the end of the 2011 growing season, the low-grow mix grasses were 4-5 inches shorter than the OVN-mix grasses and both averaged a 85% or more of soil coverage (Table 4). Weed pressure and composition was numerically higher and more diverse only with the untreated plots. In 2012, both rates of the OVN-Mix continued covering the soil and competed against weeds better than the Low-Grow mixes. Clover soil coverage was the lowest and the most weedy by the end of year 2.

At the Fowler GC site, all ground covers grew reasonably well in 2012 and 2013. Overall ground cover emergence was excellent one month after plots were seeded with a brillion. Soil moisture was adequate at the moment of planting and plots did not receive supplemental irrigation. First germination occurred with the dutch white clover seeds 11 days after plots were seeded, followed by the OVN-mix, and by the Low-Grow mix. The two Low-Grow rates covered the soil better than the two OVN-mixes on Sept, 2012. By May 2013, soil coverage for both grass mixes was similar (regardless of the two rates tested). By the end of the 2012 growing season, the low-grow mix grasses were similar in height than the OVN-mix grasses and both high rates tested averaged a 68% or more of soil coverage (Table 5).

Dutch clover germinated and established quickly than both grass mixes at the GC Fowler site. It can become a weed problem in the in-row spacing. Clover control has been difficult with herbicides, even with glyphosate, and could increase soil nitrogen levels in the tree-row spacing. However, it was the GC treatment that most impressed the grower by the end of the year 1. By May 2013, the clover treatment had almost completely suppressed weeds in these plots.

When management practices for establishing a ground cover were rigorously executed in a timely manner and with the right seeding equipment (early in May 2, 2012 at the Fowler site or late in August 15, 2011 at the Lamont site), ground cover establishment was secured for this study. 2013 weed coverage data (%) showed that the late summer establishment (Lamont site) was more effective and reduced weeds more than the early summer establishment at Fowler. Any annual weeds that may have grown were likely killed by frost before they produced flowers and seeds in the fall of 2011.

Herbicide treatments

No herbicide program in these plots gave season long control. But there were differences in the number of post-emergent herbicide applications required depending on the residual herbicide used in the spring shown in Tables 8-9. The timing of application of residual herbicides depends on rainfall incorporation to be most effective. Irrigation definitely reduces the residual herbicide effect.

Prowl or Surflan alone will provide about 30-40 days of weed control; the higher rate, the longer control. Without irrigation, 2-3 additional burndown treatments will be necessary, but with irrigation, 4. Common Ragweed was the first weed species to emerge in these treatments without the Chateau or GoalTender. Adding Chateau (12 oz./acre) to Prowl or Surflan will extend effective control and broaden the spectrum of weed control for 40-50 days. These treatments needed 3 burndown treatments with irrigation, but only 2 without irrigation. Adding Goaltender (3-4 pts) to Prowl or Surflan will extend effective control and broaden the spectrum of weed control for 60-70 days and will need 2-3 additional burndown sprays without irrigation, and 3-4 with irrigation. Matrix for use in trees established for 1 season at 4 oz./acre provided long term control, 60-90 days in 2011, but in 2012, only 40-50 days if alone or mixed with Surflan. When Goaltender was added to Surflan/Matrix, the control window increased to 105 days in Mason’s plots needing only 1-2 post-emergent burndown treatments. Treatments without irrigation using Matrix or a combination required usually 1 burndown application, but in irrigated plots, required 4 added sprays.

Alion (registered for use in trees established 3 years) provided 79 days of control in 2011 at Mason’s, but only 44 days in 2012. Both years, the Alion treatments only required 1 additional burndown treatment. Alion plots were covered with moss and did not have winter annuals germinating for the winter through April resulting in the lowest seasonal percent of weed cover. Sinbar treatments resembled Prowl or Surflan plots in residual control and required 4 burndown sprays with irrigation, and 3 without irrigation. Diuron + simazine (low rates) was the cheapest treatment at Mason’s, lasting over 2 months, and required 2 additional treatments but it is important to watch for resistant weeds. The percent weed cover data are shown for all the evaluation dates in Tables 10 and 11.

Evaluation of herbicide treatments for tree growth and trunk damage

There was a significant reduction in tree growth in new apple plantings if left weedy. However, the data revealed less difference in tree growth in 1-yr established trees at Mason’s in 2011. Therefore, newly planted trees are most sensitive to weed competition. Trunk cross-sectional area (TCSA) means for each treatment are shown in Tables 12-15 for the 1st and 2nd seasons of this project. The average TCSA of untreated plots at Lamont’s was 3.8 cm2 compared to the largest trees in the Prowl + glyphosate treatment of 7.7 cm2 after 2 seasons of growth; at Mason’s, 5.4 cm2 in untreated plots compared to the largest trees,10.2 cm2, found in the Alion plots, followed by 8.6 cm2 in the Prowl plus paraquat plots. Tree size nearly doubles if weeds are kept at bay.

The reduced tree growth as measured by trunk cross-sectional area will impact on the following season’s capacity to carry fruit. When crop load is adjusted to 4 apples per cm2 of trunk cross-sectional area (TCSA), this will translate to reduced profitability and slower payback on establishment costs! After 2 years, the potential number of fruit per tree was nearly double in the best weed control plots compared to the weedy check, 31 vs. 15 at Lamont’s, and 41 vs. 22 at Mason’s. The potential crop load after the second leaf for each treatment is shown in Figures 1-4.

There was no statistical difference in incidence of trunk damage among treatments at Lamont’s but there was trunk damage that appeared as slight flaking of the bark that may have resulted from the Gramoxone burndown treatments applied in 1, 3, 10, 11, 12 (although no trunk damage in Trt 10) when the daytime temperatures on Jun 20, 2012, reached 87oF for several hours that day. No apparent trunk damage was recorded at Mason’s.

Evaluation of changes in soil health in herbicide treatments

The soil health data gathered are strictly preliminary data with regard to impact on soil health in 2 seasons of a perennial crop where little to no soil disturbance happens after planting orchards. The only difference in production practices between the farms is the annual application of compost to tree rows at Mason’s. No heavy mulch treatments were applied, but some herbicide treatments certainly left more weed residue on the surface of the soil. Not all treatments were tested but soil health test data was gathered in four treatments: the untreated check (Trt 15, handweeded at the end of the growing seasons), Prowl/Chateau + Gly (Trt 4), Surflan/Matrix/GoalTender + P (Trt 10), and Sinbar + P (Trt 11) at each location. The data are shown in Table 16-17. The soil type at Lamont is 55% silt, 36% sand, and 9% clay, and the overall soil health quality score started at 68/100 (Medium). In 2012, after 2 seasons, the overall soil health quality score went down to 52-55/100 (LOW) but no difference among treatments tested. The soil at the Mason site was 47% silt, 44% sand, and 9% clay, and started with the overall soil health quality score started at 74/100 (High). In 2012, after 2 seasons, the overall soil health quality score went down to 59-69/100 (Medium) but no difference among treatments tested.

The physical soil health indicators tested included aggregate stability (%), available water capacity (m/m), surface hardness (psi) and subsurface hardness (psi). At Lamont’s, the aggregate stability increased after 2 seasons in all treatments tested. There was no significant change in available water capacity in all treatments tested compared to the baseline test. The surface hardness and subsurface hardness increased significantly in all treatments tested indicating a hard pan at 9 inches deep. The water infiltration tests conducted in the field on the untreated check and the Surflan/Matrix/Goaltender plots showed more potential water infiltration (in/hr) in untreated plots due to more roots trails in the soil (before handpulling weeds), 7.3 in/hr compared to the Surflan/Matrix/Goaltender plots infiltration rate of 5.6 in/hr. At Masons, there was a slight decrease in aggregate stability, more in the herbicide plots than the untreated check after 2 seasons indicating a potential to form a surface crust after a hard rain reducing water infiltration and increasing potential runoff. There was an increase in available water capacity in untreated and Sinbar plots. The surface hardness remained the same, but the subsurface hardness increased significantly in all treatments tested indicating a hard pan at 9 inches deep. The water infiltration tests conducted in the field on the untreated check and the Surflan/Matrix/Goaltender plots showed twice the water infiltration (in/hr) in untreated plots due to more roots trails in the soil (before handpulling weeds), 8.2 in/hr compared to the herbicide plot of 4.6 in/hr.

The biological soil health indicators tested were organic matter (%), active carbon (ppm), potentially mineralizable nitrogen (microgramsN/gdwsoil/week), and a root health rating (1-9 best). At Lamont’s, the organic matter decreased slightly in herbicide treatments, but no change in the untreated plots. The active carbon available as an energy source for soil microbes increased from “low” rating in baseline test to moderate level in the untreated plots; there was a slight increase in herbicide treatments but still at a “low” level. The potential mineralizable N (an indicator of the soil microbes’ ability to convert N into ammonium to be used by plants) decreased significantly in all herbicide treatments tested after 2 seasons, and decreased by 50% in untreated plots. The overall root health indictor using beans as indicators of pathogens in soil had no change after 2 seasons. Lamont’s had very low soil biological activity rating in residual herbicide plots, but better activity in untreated weedy plots. At Mason’s, the organic matter decreased in herbicide treatments, but increased in the untreated plots. The active carbon increased in the untreated plots. The potential mineralizable N decreased significantly in all treatments tested after 2 seasons. The overall root health indicator improved slightly after 2 seasons.

At Lamont’s, all chemical nutrient indicators were scored as “high” except for the extractable phosphorus which decreased by more than 50% compared to the baseline test. If the extractable phosphorus is less than 4.5, there is concern for availability of phosphorus to plants, a value greater than 25 is a concern for runoff. The chemical nutrient indicators at Mason’s were all scored in a “high” rating. Although, there was an increase in pH from 6.2 to > 7.0 after 2 seasons in treatments tested.

Evaluation of perennial weed control

The evaluation of the new planting site in 2013 for perennial weeds was done too early in the season to reveal any substantial perennial weed problem since they had not yet started to emerge. The only weed detected was nutsedge. An evaluation of the field later in the summer season may show some perennial weeds, but since there was no “untreated check” in the corn planting, no differences will be detected, only observations. We also noted that with all the disking, it would be likely that some of the weeds could be dragged past the GPS waypoint. The waypoints have a radius of about 20 ft.

After 2 seasons of using the same residual herbicides and post-emergent herbicides in plots at Lamont’s and Mason’s, the proportion of perennial species among all weed species identified in the plots was calculated and multiplied times the % weed cover for the reading in mid-August to estimate the percent weed cover by perennial weeds. See Table 18. Although this is not to my knowledge a formal method of measuring, it does provide some insight into the perennial weed pressure among herbicide treatments. Of course this is only a snapshot in a whole season of weed development. The untreated weedy check plots clearly had the greatest % weed cover by perennial weeds, and the greatest number of perennial weed species. In the Lamont site, the most common perennial “weed” in the plots was the Dutch clover planted as the ground cover treatment in the row middles plots followed by narrow leaf plantain, nutsedge, Canada thistle, curly and broadleaf dock, and dandelion. The clover can be stunted by application of glyphosate and paraquat but does not actually kill the clover. The Mason plot had horsenettle, followed by Dutch clover from ground cover treatments, dandelion, narrow leaf and broadleaf plantain, and broadleaf dock. Horsenettle is a difficult weed to control as it has a very deep root system and will produce seeds for new plants. The plots with no horsenettle were the Prowl plus 2 apps of glyphosate or Prowl plus Chateau plus glyphosate. Likely the glyphosate was doing the work. Surflan/Matrix/GoalTender plus Gramoxone, needed one touchup with Gramoxone. Matrix plus Gramoxone in spring followed by Rely also provided good control of horsenettle. Likely Matrix is providing some residual control.

Research conclusions:
Ground cover seeding options

Ground cover species performed variably in this project, especially in 2011 (in SARE Partnership grant ONE11-138). Weed pressure and hot conditions were intense with the spring planting in 2011. This effect was more pronounced at the Mason site where none of the treatments were successfully established by 2013. When the seeding was delayed to late summer in August 2011, both mixes performed well without any hand weeding or irrigation and had much less weed pressure at the end of the growing season. All the grass species that were fall planted in 2011(Lamont site) and in the spring of 2012 (Fowler site) had excellent germination and growth (much slower for the Low-Grow mix at the Lamont site).

Evaluation of weed coverage (%), GC coverage (%), and GC height (inches) in year 2 and 3 determined that the Low-Grow Mix is not yet a better replacement to the widely used OVN-Mix chosen by the majority of apple growers in Western NY. The Low-Grow mix is perhaps a more difficult grass mix to establish because it contains small, lower vigor seedlings that produce initially less above ground biomass. Planting a low grow mix with a nurse crop such as annual ryegrass or oats at a low seeding rate would be more beneficial. Once the low grow mix at the Fowler site will be well established (by the end of 2013 or early spring in 2014), we will possible determine which grass populations and seeding rates (16 versus 22 lbs/acre) should be considered for further comparative studies with the more traditional OVN-mix seeds.

This ground cover project confirmed the following field experiences:
(1) Ground covers (grasses) should be planted in either early in the spring or late in the summer (August 15-Sept. 15) in Northeastern apple fruit regions.
(2) Fall planting leads to much lower weed competition than spring planting in the Northeast.
(3) Late summer establishment is more convenient because the soil is warmer (than an earlier spring in NY State), which will provide for rapid seed germination.
(4) Late summer establishment is also more convenient because any annual weeds that may grow will likely be killed by frost before they flower and produce seed.
(5) OVN-Mix and the Low-Grow Mix did not establish well and did not compete with weeds (under severe hot conditions in early spring in 2011).
(6) Low-Grow Mix is slow to establish and grow less than the OVN-Mix (under normal growing conditions).
(7) OVN-Mix performed well and established a cover more quickly than the Low-Grow Mix (under normal growing conditions).
(8) Early spring planting of an apple tree and a ground cover without irrigation is critical to secure germination, tree root establishment, and establishment of a ground cover in the Northeast.
(8) Dutch clover germinated and established quickly than both grass mixes at the three ground cover sites. It was the GC treatment that most impressed the grower cooperator, but blooming clover may become more of a problem with carbaryl applications at thinning time due to bee toxicity.

Herbicide treatments
  • Growers and consultants had several opportunities at field tours, and winter educational events to observe differences among residual herbicide treatments in new, high density plantings. This project helped growers get more familiar with some of the new herbicides registered and different combinations which will result in better herbicide resistance management if they rotate herbicide mode-of-action.

    This project also helped to develop weed management expertise in extension specialists that will contribute to the development of the Cornell Pest Management Guidelines for Commercial Tree Fruit Production in the future.

Herbicide affects on tree growth and trunk damage
  • The seed money for these Partnership grants has demonstrated the critical need for weed control and the negative impacts if not implemented in new, high-density apple plantings. This project has demonstrated that there is serious reduction in tree growth if weeds are not controlled in the early years.

    The reduced tree growth translates into the reduced profitability and later payback on investment costs. After 2 years, the potential crop value per acre in the herbicide plots with the greatest tree growth was increased by $2300 over the untreated weedy checks in the super spindle planting at Lamont’s; $1200 per acre in the tall spindle planting at Mason’s.

    Growers have become increasingly aware of how critical weed control is in high density plantings.

    An additional outcome is that a separate project was funded by the NY Apple Research and Development in 2013 to look at the critical timing of weed control in high density apple plantings.

    These projects were not able to identify specific trunk damage or other negative impacts of using glyphosate in these orchards in spite of not using any trunk protection such as treeguards or white paint where glyphosate was used.

    Trunk damage was only noted in plots without glyphosate.
    There were no observations in the soil health testing that indicated any difference in biological activity in soil in treatments with/without glyphosate.

Changes in soil health from herbicide treatments
  • This was an attempt to adapt the soil health parameters used in annual crops with tillage/minimum tillage to see if any particular indicators were apparent.

    The only indicator that seems to be universal is the potential for the hard pan at the plow depth at 9 inches deep may be a cause of restricted water drainage and root penetration. Perhaps growers are using subsoilers before planting to break up any hard pan.
    Perhaps the Cornell Soil Health team can review the data to determine any future areas of study that will impact on perennial cropping systems.

Control of perennial weeds
  • This short-term study was the initial attempt to understand perennial weeds in perennial cropping systems but not sufficient to draw any real conclusions for apple plantings.

    There is a clear tendency for perennial weeds to become more numerous in perennial cropping systems with no soil tillage.
    Preplant cropping with annual crops should help to reduce the perennial weed pressure where herbicides that do not carry over can be used in row crops to reduce their growth.

Participation Summary

Education & Outreach Activities and Participation Summary

Participation Summary

Education/outreach description:
  • A ground cover article will be submitted to the NYFQ magazine this year. The suggested titled is “Advantages and Disadvantages of Current Grass Ground Cover Options for High Density Apple Orchards in Western NY”. The authors are Miranda Sazo and Tee.

    200 growers attended the LOF Summer Tour in July, 2012 to see the side-by-side herbicide treatments and learned about new vs. old residual herbicides.

    40 fruit extension and research workers learned about weed control options and impact on tree growth from this project at the Great Lake Fruit Workers Conference in November, 2012.
    160 growers attended the Empire State Producers EXPO in January,2013, to hear about the results of the herbicide testing, “What is the best herbicide for new plantings?”
    150 growers and consultants heard about weed management in young, high density orchards at the Eastern NY Winter Fruit School, February, 2013.
    220 growers and consultants from eastern US heard about the economic impact of weed management derived from this project at the March, 2013 In-Depth Precision Orchard Management Summit.
    600 growers in the northeast will learn about the impacts of weed control in a summary article written for the New York Fruit Quarterly, Winter 2013.

Project Outcomes

Project outcomes:
Ground cover seeding options

Estimates are made and the optimal seeding rate of a ground cover grass mixture for this analysis is 20lbs/acre. The Low-Grow mix is a more expensive grass seed than the OVN-mix. The current prices for a 25lbs seed bag are $119 dollars for the Low-Grow mix and $46 dollars for the OVN-mix. The cost of buying a Low-Grow mix seed for one acre is $ 96 dollars versus $37 dollars for an OVN-mix seed.

At the Fowler site the commercial rate of OVN-mix used for this study was approximately 16lbs/acre (a higher rate was tested of 22lbs/acre for the OVN-mix and the Low-Grow mix). A few fruit growers have commercially used even lower OVN- mix rates and have established an acceptable grass ground cover with 12-14lbs/acre. Higher OVN-mix rates (@ 25lbs/acre) are recommended for more steep slopes where erosion is a severe problem.

Theoretical savings of using a Low-Grow mix: A grower would require mowing a high density orchard (3ft X 12ft) approximately 4-6 times a year. Assuming a Low-Grow mix would be established adequately by the second year and may need to be mowed less often than the OVN-mix, it may (untested) save 2-3 mowing/year (less fuel costs, less labor time costs, possibly less orchard-floor maintenance) and for the following 13-14 years of orchard life. This study showed that the Low-Grow mix did not establish better than the OVN-mix and at a same seeding rate by year 2. The OVN-mix is still the best available grass mixture and the cheapest option that secures a solid grass cover (assuming all orchard-floor practices are executed correctly and on time). The OVN-mix is by far the most popular grass mix used by fruit growers in Western NY. As an example, there is one distributor that sold 1,700 lbs of OVN-mix seeds in Wayne County this 2013 Spring. The recommended seeding rate was 20lbs/acre.

Herbicide treatments

The cost of herbicide inputs are reported in Table 19. Rod Farrow, Lamont Fruit Farms, has calculated that it costs about $60 per acre to manage weeds in a high-density apple planting including application and materials costs. He estimates his cost of production is typically $6000 per acre, so weed management is only 1% of that cost. Therefore, the herbicide cost that ranges between $7.50 – 34.00 per acre is insignificant. It is the lack of weed control that will cost the growers money!

The potential economic loss due to poor weed control in the first few years in the Lamont orchard can result in a delay in the breakeven year of investment from year 13 in the best weed control treatment vs. year 15 in the worst weed control treatment, resulting a loss of $4500 per acre in Net Present Value in year 15 shown in Table 20. In the Mason site, if a mature yield of 1000 bushels per acre, the breakeven year of investment from year 22 in the best weed control treatment will be delayed in the worst weed control treatment until year 29. If 1200 bushels per acre, the breakeven year of investment will occur in year 15 in the best weed control treatment vs. year 19 in the worst weed control treatment, resulting a loss of $6000 per acre in Net Present Value in year 15. Weed control is critical to the profitability of new, high-density apple plantings.

Farmer Adoption

  • Growers have commented on program evaluations that they are more aware of herbicide options and timing.
    Growers learned about how poor weed management will result in potential crop loss in their new plantings.
    Growers want to use alternatives to rotate mode-of-action of herbicides to prevent resistant weed populations.
Assessment of Project Approach and Areas of Further Study:

Areas needing additional study

  1. The GC Fowler trial comparing side-by-side both ground cover mixes (OVN-mix and Low-Grow mix) and two seeding rates (16 and 22 lbs/acre) needs to be evaluated by the end of year 2, 3, and 4 (weed coverage (%), ground cover coverage (%), and ground cover height (inches)).
    Ground cover established biomass production should be evaluated in a monthly basis at the Fowler site in year 2, 3, and 4.
    Establishing a grass ground cover trial at the Geneva Agricultural Research Station will facilitate the correct timing for mowing at a targeted grass height (inches).

    Ground cover plots could be established at the organic apple research trial recently planted in Geneva last year.
    Need a long term project to study the impact and control of perennial weeds in tree fruit.
    Need a long term study to identify the critical weed control practices in high-density fruit plantings starting with pre-plant site preparation.
    Need a long term study to look for effects of glyphosate on tree and soil health.

Any opinions, findings, conclusions, or recommendations expressed in this publication are those of the author(s) and do not necessarily reflect the view of the U.S. Department of Agriculture or SARE.