Integrating ground cover crops and new herbicide strategies (conventional and organic) for tree growth and soil health

Final Report for ONE11-138

Project Type: Partnership
Funds awarded in 2011: $15,000.00
Projected End Date: 12/31/2011
Region: Northeast
State: New York
Project Leader:
Deborah Breth
Cornell Cooperative Extension
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Project Information

Summary:

This study compared the impact of various herbicide strategies and ground cover systems on growth of newly planted and 1-yr high density apple orchards. At two commercial sites, three replications of six groundcover treatments were manually seeded, maintained, and mowed when needed by grower cooperators. Groundcover treatments were randomly assigned to strips between tree rows in experimental units of approximately 50 ft. plots with 20-25 adjacent trees around the plot. The GC treatments were: (1) OVN mix – Orchard-vineyard-nursery composed of 40% proprietary perennial rye, 30% creeping red, 30% chewing fescue seeded at 25 lbs/acre, (2) OVN mix (same grass mix as described) seeded at 75 lbs/acre, (3) Low-Grow Mix (50% firefly hard fescue, 20% intrigue chewing fescue, 20% azure sheep fescue,10% minotaur blue hard fescue) seeded at 50 lbs/acre, (4) Low-Grow Mix (same fine leaf fescue mix as described) seeded at 100 lbs/acre, (5) Native weed vegetation as established by mowing at each site, and (6) Dutch White Clover seeded at 20 lbs/acre.

The first growing season of this project revealed the strengths and weaknesses of and variability in weed species that grew through various herbicide treatments in young, high-density apple plantings. It also proved how the lack of weed control impacts negatively on tree growth. The side-by-side treatment comparisons demonstrated how long the various residual herbicide treatments were effective, how soon a post-emergent treatment was necessary, and consequently, how often treatment was necessary through the growing season. The collaborators gained a realistic perspective of establishing ground cover between tree rows, the best timing for establishment, and how long it takes for germination for each seeding type.

Herbicide Strategies

There were no weed control treatments in newly planted or 1-year established orchards that lasted season long. Treatments using Matrix or Alion in the 1st year established orchard provided the longest window of control. The combinations of Chateau or Goaltender (plus Prowl or Surflan) in the newly planted orchards required only a single follow-up post-emergence treatment. Other treatments required 2 post-emergence applications. The shortest residual treatments were the Prowl or Surflan alone. The longer weed control season in the Mason 1-year established orchard resulted in most herbicide treatments needing 2 paraquat applications compared to 1 paraquat application in most of Lamont treatments with a month shorter weed control season in the newly planted orchard.

GreenMatch, the OMRI certified organic herbicide, provided the same weed control as the untreated check in newly planted orchard, and slightly better in the 1-year established orchard, but the tree growth was the same as untreated check in newly planted trees. It was difficult to keep up with applications of GreenMatch which required applications every 2 weeks or more often to control succulent germinating weeds. High rates of material and cost will deter use of GreenMatch.

Tree growth in the untreated checks was reduced compared to herbicide treatments. There was a greater negative impact on tree growth in the newly planted orchard than the 1- year established orchard.

Orchard Ground Cover Establishment

This study showed that two grass mixes can establish and compete with weeds differently when monitored from May 2011 until June 2012. The Orchard-vineyard-nursery(OVN)-mix of rye and fescues treatment (regardless of the two rates tested at the sites) grew taller and a little more thicker than the low-grow mix of fine fescues. The OVN-mix(if managed individually) needed to be mowed more frequently (it was always taller than the low-grow mix) and did not establish much better than a low-grow mix one year after seeding. Interestingly, the clover treatment (at both GC sites) showed to be a good alternative for groundcover management. It established and competed even better than the two GC grass mixes studied in this project. At the beginning of the second season and after repeated freeze events in 2012 (this measured only at the GC Lamont site), the low-grow mix of fine fescues was still less dense and did not compete better against weeds than the OVN-mix. There is a need to continue evaluating the low-grow mix (and also the clover plots) as it grows and establishes very slowly compared with the OVN-mix under Northeastern conditions. An acceptable low-grow mix establishment free of weeds by the end of the second year and a potentially less demanding ground cover option for mowing may save time, production costs, and be more appropriate to NY fruit growers.

Introduction:

Thousands of acres of apples in NY and across the country are planted at very high density orchards with 1000-2000 trees per acre with smaller root systems, narrower tree canopy, to produce more high quality fruit beginning in the 2nd leaf. But from these intensive systems arise questions about the best ground cover and weed management program. Advisory committees have listed ground cover management and weed control as one of the top 5 pest management issues that impact on their profitability. The driving factors for these questions include the development of simazine and glyphosate-resistant weeds, potential groundwater pollution with older residual herbicides, the newly reported risk of glyphosate application resulting in bark injuries and tree death, and the concern for soil health in orchards with such restricted root systems.

Research by Ian Merwin (1997, see citation in references) has shown that minimizing weed competition under the trees and planting the right ground cover (GC) between the rows will impact tree growth, irrigation scheduling, orchard nutrition, vole control, soil health factors, general tree health, and ultimate profitability of orchards. This original work was done in semi-dwarf orchards at 3x6 m spacing, and has not been tested in higher density, super spindle or tall spindle orchards planted at 0.5-1x3 m spacing. The objective is to adapt the Cornell research on semi-dwarf systems to the more intensive high density systems and measure the impact of 6 ground cover treatments between tree rows and up to 14 herbicide strategies within the tree rows on tree growth, tree health, and soil health.

NY growers rely heavily on a limited number of older, less expensive herbicides. The continued use of simazine and/or diuron has led to herbicide resistance in several broadleaf weeds. Additionally, there have been concerns about the older herbicides leaching into water sources, and degrading soil health with residual herbicide strips. In recent years, new herbicides have been registered for use in tree fruit crops with different spectrums of weed control and safer environmental profiles. Several organic herbicide products have also appeared on the market. These new options for organic and conventional growers are best evaluated in side-by side demonstrations in replicated plots.

Integrated Fruit Production protocols have promoted the use of post-emergent herbicide programs, discouraging the use of pre-emergent residuals. Consequently, glyphosate has been a major component of weed management over the past 20 years but if used alone will result in development of glyphosate-resistant weeds such as marestail. Glyphosate is often used in combination with 2,4-D to control perennial weeds in this perennial crop. Glyphosate kills plants by blocking a critical enzyme in the shikimic acid pathway, reducing the production of proteins and phenolics, plant compounds that provide defense against pathogens and contribute to tree winter hardiness. Bark splitting has been documented by Dr. Hannah Mathers, Ohio State University (2011, see citation in references), after glyphosate applications in ornamental tree species including crab apples indicating high risk of trunk damage in high-density apple orchards. Non-target effects of glyphosate on apples have been suspected since 2004, including trunk cankers and tree death. This indicates the importance of understanding how to integrate residual herbicides into a program to reduce the number of required post-emergent treatments and resulting risk in the use of glyphosate.

Climate change scientists are forecasting more extremes in rainfall, droughts or heavy rains, resulting in more runoff and less useable water in orchards. Understanding how various herbicide treatments may impact on water permeability in the tree row and in the row middle as effected by the ground cover species will help growers manage irrigation needs better. The right balance in GC and herbicides will be required and is a more long term goal of this work.

Herbicides featured in this project include: Prowl H2O, Surflan AS, Sinbar, diuron and simazine, Chateau WDG, GoalTender, Matrix, Alion, and the organic herbicide, GreenMatch.
See Appendix 1 for more information on specific herbicides.

Project Objectives:
Short Term:

1) show strengths and weaknesses in side-by-side herbicide treatments in young plantings
2) identify the pros and cons of various ground cover seeding options

Long Term:

3) evaluate herbicide treatments for trunk damage from glyphosate use
4) evaluate changes in soil health properties

Cooperators

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

Research

Materials and methods:

With the help of 2 growers, 2 on-farm demonstration sites were set up where the sustainability of treatments can be evaluated in replicated plots for the short term, and potentially for a longer term after they are established. Before establishing the plantings, required dolomitic lime and N-P-K nutrients was applied to both sites. Calcium nitrate was applied beneath each tree at the rate of .25 lb./tree after planting. During subsequent years, recommended rates of N will be applied each spring at budbreak and K each November. Other supplemental nutrients are applied by foliar application based on foliar nutrient analysis of soil and leaves. Orchard pest management programs will be the same for the whole planting based on disease models and scouting results.

Soil Health: In Spring, 2011, a composite soil sample was collected at each site for a baseline analysis of various measures of physical, chemical, and biological properties of the soil using the Cornell Soil Health protocol. In March, 2013, soil health measurements will be repeated for a range of herbicide treatments resulting in 0-10%, 40-60%, and 80-100% weed cover. The major soil health measurements relevant early in the study will be soil compaction using a soil penetrometer, water permeability, water holding capacity and soil nutrients.

Doug Mason of Mason Farms planted Snappy Mac on Bud9 rootstocks in 2010 at a spacing of 3.5 x 14 ft. in a tall spindle system.

Rod Farrow of Lamont Fruit Farm planted Gala on M9 at 2.3 x 11 ft. on May 12, 2011 in a super spindle system.

Herbicide Strategies

Doug Mason of Mason Farms planted Snappy Mac on Bud9 rootstocks in 2010 at a spacing of 3.5 x 14 ft. in a tall spindle system. Herbicide test plots were established in April, 2011, and pre-emergence treatments were applied April 22 followed by nearly 6 in. of rain the following 30 days and total of 10 in. of rain for the 3.5 month period after the residual herbicides were applied. Before the residual applications, this orchard had a carpet of winter annual weeds mainly annual bluegrass (Poa annua) and hairy bittercress (Cardamine hirsuta).

Rod Farrow of Lamont Fruit Farm planted Gala on M9 at 2.3 x 11 ft. on May 12, 2011 in a super spindle system. Herbicide applications had to wait for a window for treatment after soil settled and applicators could walk on open ground after the heavy rains. The residual herbicides were applied to clean ground on May 23. There were 3.5 in. of rain the first 30 days after the application, and 7.2 in. of rain over the 3 month period after residual herbicides were applied. This orchard also had trickle irrigation installed and was operating during the month of July when there was no precipitation.

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 resulting in 34 gpa at Lamont’s and 23 gpa at Mason’s. Herbicide strips in rows at Mason’s were 3 feet wide, and Lamont’s, 2 feet. All post-emergent treatments included the use of a non-ionic surfactant (Induce) and all glyphosate mixes included AMS even though water used for treatments was municipal. Treatments are listed in Appendix 2 - Herbicide Treatments.

Percent weed cover was evaluated at every 2-3 week intervals. When weed cover reached a threshold of 20-30%, post-emergence treatments were made using paraquat in most treatments or glyphosate in 2 treatments. The tables below show the number of days the residual was effective before the first paraquat/glyphosate application was needed (DAT). Statistical analysis was conducted using Anova, and Tukey HSD mean separation, to look for differences in weed control on each date sampled.

The impact on tree growth was evaluated by measuring the tree caliper 30 cm above the graft union in April and after leaf fall. The trunk cross-sectional area was calculated for April and leaf fall and the percent increase was calculated. Statistical analysis was conducted using Anova, and Tukey HSD mean separation.

Orchard Ground Cover Establishment

Two groundcover trials were started on 2011.

The Mason GC trial was manually seeded on June 9, 2011. It was reseeded to improve establishment of plots on March 16, 2012.
The Lamont GC trial was seeded on August 15, 2011.

At both sites, three replications of six groundcover treatments were manually seeded, maintained, and mowed when needed by grower cooperators. Groundcover treatments were randomly assigned to strips between tree rows in experimental units of approximately 50 ft. plots with 20-25 adjacent trees around the plot. The GC treatments were: (1) OVN mix - Orchard-vineyard-nursery composed of 40% proprietary perennial rye, 30% creeping red, 30% chewing fescue seeded at 25 lbs/acre, (2) OVN mix (same grass mix as described) seeded at 75 lbs/acre, (3) Low-Grow Mix (50% firefly hard fescue, 20% intrigue chewing fescue, 20% azure sheep fescue,10% minotaur blue hard fescue) seeded at 50 lbs/acre, (4) Low-Grow Mix (same fine leaf fescue mix as described) seeded at 100 lbs/acre, (5) Native weed vegetation as established by mowing at each site, and (6) Dutch White Clover seeded at 20 lbs/acre.

The Mason GC trial was mowed on August 4, 22, Sept.28, and Nov 15. The Lamont GC trial was mowed at the end of the 2011 growing season on Nov. 18.

At the Lamont GC site, groundcover coverage (%) and weed biomass coverage (%) were evaluated on 9/30/11, 5/3/12, and 5/22/12. Groundcover height (inches above ground level) and weed population (number of weeds per sampled area) were evaluated on 5/3/2012 and 5/22/2012. At the Mason GC site, groundcover height (inches above ground level), groundcover coverage (%), and weed biomass (%) were evaluated on 8/22/11 and 6/6/12.

Research results and discussion:
Herbicide Strategies

Residual herbicide efficacy depends on incorporation of the herbicide into the seed germination zone of the soil, and the longevity of the control can depend on the amount of precipitation after the application. Figure 1 (Appendix 3- Precipitation records) shows the daily precipitation and accumulated rainfall for Lamont Fruit Farm and Mason Farms from NEWA weather data after the residual herbicide was applied and though August, 2011. It was a very wet growing season with the exception of the month of June and much of July. There is no data for the irrigation provided for Lamont Fruit Farm.

The longer season in Mason’s 1-year established orchard resulted in 8 of 12 herbicide treatments needing 2 paraquat applications compared to a single paraquat application in 5 out of 9 Lamont treatments. Tables 1 & 2 show the percentage of weed cover in each treatment for several dates through the season and the number of days the residual was effective before the first post-emergent herbicide application was needed (DAT). They also include the number of post-emergent applications (# P sprays) needed for each treatment, and the percent increase in trunk cross-sectional area (% increase in TCA) for each treatment.

The first treatments to break under the rainfall were Prowl and Surflan with ragweed and foxtail the first to germinate. Although different rates were not compared, the higher rate used, the longer the effective residual. These herbicides have no burndown activity, so if any weeds were already germinated at the time of application, there would not be any effect. More rainfall at Mason’s, 4 inches after the first application, cut the period of effectiveness short compared to less rainfall at Lamont’s, 2 inches within 30 days of the application before irrigation was installed.

The next treatments to break were Prowl/Surflan with Chateau at 8 oz./acre. If a higher rate of Chateau was used, it would have lasted longer. At Lamont’s the Surflan + Chateau lasted longer than Prowl + Chateau, but this was not consistent in the Mason plots. Treatments with Chateau burned back the winter annual weeds at Mason’s but the first weeds to break through the treatments were grasses.

The Prowl/Surflan combination with Goaltender (PPO, with pre- and post-emergent control) added 2-3 weeks of control to Prowl/Surflan alone providing almost 2 months of control at Lamont’s and 2.5 months at Mason’s. GoalTender also has burndown activity which took care of winter annuals present.

There were 3 treatments at Mason’s that included Matrix, but there were only 2 Matrix treatments in the Lamont planting in combination with Surflan included to observe any impact on tree growth as expected from label restrictions for use in 1- year established trees. The 2 treatments with Surflan included at Lamont’s lasted 57-65 days possibly due to the irrigation; but all 3 treatments with Matrix at Mason’s lasted nearly 3 months. The Matrix application alone was sufficient for control with potential for cost savings. This was the longest lasting treatment with bindweed, prostrate knotweed, and foxtail breaking through.

Sinbar plots had foxtail, lambsquarters and pigweed breaking through treatment. This low rate of Sinbar weed control held for 87 days at Masons; but only 40 days at Lamont’s with lambsquarters, purslane and bindweed breaking through.

All treatments at Mason’s except for the Matrix and Alion treatments required 2 post-emergence treatments. The GoalTender/Prowl or Surflan combinations and Surflan plus Chateau treatments at Lamont Fruit Farm only required 1 post-emergence application. The growing season at Lamont’s was a month shorter to combat weeds.

Tree growth measurements in trunk cross sectional area (TCA) in cm2 before the growing season compared to the end of the growing season are shown in Tables 1 and 2 as % change in TCA. The greatest statistical increase in TCA at Lamont’s was in the plots with Prowl/Surflan, Chateau, GoalTender, and Sinbar. The Surflan plus Matrix treatment was numerically better than the untreated check but not statistically separated, but when combined with GoalTender, was one of the better (although most expensive) treatments. Green Match and the untreated check had the least increase in TCA due to the weed competition.

Tree growth measurements in Mason’s Farm did not show much separation but the untreated check had only 93% increase in TCA, statistically lower than the increase in Surflan/Prowl alone, Surflan + GoalTender, Matrix, and Alion plots, with a range of 148-165% increase in TCA. All other treatments were not statistically different from the check or the best treatments. The reduced effect on tree growth in this plot was likely due to the established root system by the second year in the orchard, with roots developing below the seed germination and root zone, reducing the potential competition by the weeds.

In plots using glyphosate for post-emergence weed control, there was no detectable impact on tree growth. They were statistically grouped in the treatments with the best tree growth in both plantings. No bark cracking was noted to date.

Orchard Ground Cover Establishment

This 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 seeded after the hot, dry weather. Consequently, the GC plots were not well established at the Mason site. Temperatures were unseasonably warm in Western NY with over 15 days at 90F or above during the June and July months of 2011. The Mason GC site was not terminated by the end of 2011 and was reseeded (same treatments, rates, and method of seeding) on March 16, 2012 hoping for some “frost seeding” to improve the stand.

Mason GC site: 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. 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 2011, respectively. By the end of August, the OVN-mix and the Low-Grow mix treatments did not successfully establish and were severely contaminated by summer weeds and crab grass (not by fine fescues as desired). Soil coverage of fine fescues was less than 53%, averaged a height of 5.5 inches, and had more than 47% of weed coverage for both mixes on August 22, 2011. Several frost events occurred after experimental plots were reseeded on 2012. Mason GC plots grew and established better and had an increase of 7% of more of soil coverage for both mixes on June 6, 2012 (Table 3). Interestingly, clover plots recovered by early spring 2012 and before the reseeding, and showed a 92% soil coverage and the highest height of all treatments on June 6, 2012.

Lamont GC site: All ground covers grew reasonably well in 2011. Overall ground cover emergence looked pretty good for all treatments 45 days after plots were seeded. 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. 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. OVN- treatments established better, grew faster, and covered the soil a 10% more than the low-grow mixes on 2012 season (Table 4). Again, clover had the higher soil coverage of all treatments (92%) and had the lowest number of weeds per plot by May 22, 2012. Apparently, the slow establishment of the low-grow mix facilitated the establishment of weeds as sampled areas were more weedy (the highest weed coverage was measured for trt 3 with 34% of infestation). Trts 3 and 4 had 1.5 more weeds per sampled area than trts 1 and 2.

Research conclusions:
Herbicide Strategies

Choosing herbicide treatments will depend on tree age allowed on the label, rates dependent on tree age and the desired duration of weed control, and how growers figure the cost and management of additional post-emergent control. There were no weed control treatments in newly planted or 1-year established orchards that lasted season-long, an expectation for some growers. Treatments using Matrix or Alion in the 1st year established orchard, and the some of the combinations with Chateau (Prowl or Surflan) and Goaltender (plus Prowl or Surflan) in the newly planted orchards required only a single follow-up post-emergence treatment. Others required 2 post-emergence applications. The shortest residual treatments were the Prowl or Surflan alone. The longer season in the Mason 1-year established orchard resulted in most herbicide treatments needing 2 paraquat applications compared to 1 paraquat application in many of the Lamont treatments.

GreenMatch, the OMRI certified organic herbicide, provided the same weed control as the untreated check in newly planted orchard, and slightly better in the 1-year established orchard, but the tree growth was the same as untreated check in newly planted trees. It was difficult to keep up with applications of GreenMatch which required applications every 2 weeks or more often to control succulent germinating weeds. High rates of material and cost will deter use of GreenMatch.

Tree growth in the untreated checks was reduced compared to herbicide treatments. But there was a bigger impact on tree growth in the newly planted orchard than the 1-year established orchard.

No conclusions can be made from this one-year study regarding the impact on glyphosate on tree health, but we hope to continue this project with an additional focus on controlling perennial weeds. No conclusions can be made regarding soil health among treatments, but soil health test in subsequent years may influence future weed control recommendations.

Orchard Ground Cover Establishment

We have not recommended the use of the low-grow mix or the clover. The selection of a replacement or the recommendation to use a new mix of grasses will depend on the successful establishment of the mix, sustainability of the new system, and gains on profitability with a new grass mix. We have just started to develop new tools and basic knowledge for recommending and managing groundcover for row middle vegetation and with further work will have better recommendations.

Participation Summary

Education & Outreach Activities and Participation Summary

Participation Summary:

Education/outreach description:

LOF Summer Tour, Wednesday, August 3rd, 2011 – 220 participated in the tour of cutting edge production technology of high quality apples and sweet cherries in Orleans and Niagara Counties. The tour stops highlighted grower innovations and combined grower and Cornell faculty presentations so growers could learn from growers. This was a tour for commercial fruit producers and supporting businesses. The tour featured high density apple planting systems including super spindle, tall spindle and V-axe apple planting systems, equipment innovations for improving labor efficiency, sprayer technology, new pest management technology, weed management, and all about sweet cherries. Deborah Breth presented the objectives of the NESARE project and herbicide treatments and the weed control programs funded by the NESARE Partnership Grant. Rod Farrow talked about his standard weed control and ground cover establishment practices and philosophy.

LOF Winter Fruit Schools had record attendance, with a total of 180 and 178 at Niagara (Feb. 6) and Wayne Co. (Feb. 7) schools, respectively. Participants highlighted particular topics they learned about including apple flesh bleeding, weed control alternatives and the potential damage from glyphosate, managing fire blight with streptomycin resistance and using Apogee, how to manage voles, and planting new orchards. Deborah Breth reported on “Weed Control in New and Established Orchards” – as funded by NESARE Partnership grant. Growers learned about the best herbicides to use in new and young plantings, and how weeds impact on tree growth. Growers (75%) said they were interested in learning more about weed management. Participants reported they would apply new herbicides especially in new plantings, and be more careful with glyphosate.
Deborah Breth presented Weed Identification and weed control basics to 15 participants in the Lake Ontario Future Fruit Growers monthly meeting, March 29, 2012.

Publications:
2012. Deborah I. Breth & Mario Miranda Sazo. Weed Control in Young Trees and New Herbicides for the Spring 2012, NY Fruit Quarterly. Vol. 20, No. 1. Circulated to over 1000 fruit growers in NY and the NE.

We have not published the GC results of this project (solely the weed control NYFQ article prepared by Debbie). We will write an article and will compile the results of three GC trials established in NY (GC Mason, Lamont, and Fowler sites). This second article will also add the research results of a new organic apple block established at the Agricultural Research Station in Geneva on May 21, 2012.

Project Outcomes

Project outcomes:
Herbicide Strategies

The costs of the individual herbicide programs for the year in materials are relatively inexpensive, from $25 – $45 per acre as shown in Table 5. As estimated by Rod Farrow, the cost of each application is even inexpensive, if applying 4 applications per year, it will cost about $7 per application/acre in equipment and labor cost. Therefore, herbicide and application costs will only account for 1% of the $6000/year costs to produce an acre of high quality fruit on high-density orchards.

Tree growth impact has been shown by Robinson, et al, to determine the potential crop load supported the following year. This is an important measure of the productivity of orchards in the following season. For example, research reported by Dr. Terence Robinson, et.al., proposes 4-6 apples/cm2 TCA is allowed on trees the in the second leaf. Table 6 shows the best treatment at Lamont's resulted in 3.47 cm2, with a potential for 21 apples in the 2nd year vs. the worst case in untreated plots with 1.94 cm2 supporting only 11.6 apples. To estimate the potential impact even further, we assume the return to growers is $7/bu for 88 count fruit resulting in a difference of $1100 between the best and worst herbicide treatment. Knowing the yields will not be normal in 2012 due to frost, there will be no way to validate this in a 1-year study. But it is apparent that weed control results will impact on profitability of young orchards and how soon growers will get return on investment.

Orchard Ground Cover Establishment

Frequency of mowing was not conducted separately for each of the mixes as initially proposed for 2011. Plots were mowed at the same frequency when conducted by the grower at nearby row middles adjacent to the plots. We observed that the need for mowing can potentially be reduced for the low-grow mix and some fuel/labor savings can be achieved by mowing less frequently in higher density plantings.

Farmer Adoption

Many fruit growers spoke with me after the LOF Winter Fruit Schools after they saw the benefit in tree growth in using pre-emergent herbicides and planned to use Chateau or Sinbar or Goal or GoalTender, in combination with Prowl or Surflan to get extended control and apply before bloom. Their goal was to spread the work load more evenly before, during, and after bloom. Often growers get so busy planting new orchards, planting other crops, spraying for scab and fire blight, that weed control takes low priority resulting in weed growth that is too tall for effective control and competes for the fertilizer applied to the trees. Many growers at the summer tour observed the long term control using Matrix and decided to use that for resistant weed management in established orchards as a rotational program. Reliance on glyphosate is still the major herbicide program for many growers who have not noticed the negative effects reported by others.

Of over 150 participants who responded to Turning point Audience response system at Winter Fruit Schools, 75% said they were interested in learning more about weed management. Participants reported they would apply new herbicides especially in new plantings, be more careful with glyphosate. Of 111 respondents to the paper program evaluation, 25% said they were going to make changes in herbicide strategies and look at alternative to glyphosate only programs.

Rod Farrow learned about identification of specific weeds such as marestail, curly dock, broadleaf dock, and other perennial weeds that are established in orchards. The expectation is that these are controlled before planting in previous cover crop or alternative annual crop. He said that the most important thing he learned was the potential loss of profit if he did not pay close attention to weed control in young plantings and the potential for reduced tree growth and consequently, reduced fruit production in the 3rd season.

Doug Mason is hosting the LOF Summer tour for 2012. He was interested in exploring the use of the OMRI certified herbicide for other crops, but GreenMatch was discontinued and did not perform better than the untreated check plots.

Growers have not adopted the use of other ground cover options beyond the traditional use of the OVN-mix at this moment. The low-grow mix needs to continue being monitored in the long term under on-farm and real traffic conditions.

Assessment of Project Approach and Areas of Further Study:

Areas needing additional study

Perennial weeds continue to challenge fruit growers in the perennial cropping system. It is unclear if pre-plant and site preparation herbicides can effectively control some of the more persistent perennial weeds like Canada thistle, horsenettle and the dock family. The only recourse is for growers to treat perennials with repeated paraquat, glufosinate ammonium, or glyphosate or combination with 2,4-D and risk trunk damage. This would be a bigger project starting with new fields planned for orchard in following seasons and following weed control on a longer term basis and capture orchard yields for a few years.

There is a need to continue evaluating the low-grow mix as it grows and establishes very slowly compared with the OVN-mix under Northeastern conditions. A new third trial (GC Fowler site) will compare side-by-side both mixes at a trial established in Wayne County on May 2, 2012. Soil coverage will continue being monitored at the GC Mason and Lamont sites this season.

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.