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

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

Summary

This project has been helpful to the apple industry to demonstrate how critical weed control is in the year of establishing new high-density orchards can impact on future profitability. Growers have been able to see the strengths and weaknesses of each herbicide program. We have shown growers that the cost of these herbicide programs is a very small portion of the overall production cost. Cooperators have observed that it is more important to match the herbicide strategy with the grower’s management style. The results of the project have been shared with 200 growers at each of 2 summer tours, and 300 growers at the 2012 LOF Winter Fruit School. An article was published in the NY Fruit Quarterly with the first year impact circulated to 700 industry members in the Northeast.

Objectives/Performance Targets

1. Identify the pros and cons of various ground cover seeding options
   Show 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

Accomplishments/Milestones

This season we established a new ground cover trial (GC Fowler site) 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. Our GC trial compares side-by-side both ground cover mixes (OVN-mix and Low-Grow mix) at 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 are being studied: Trt1 (untreated-natural vegetation), Trt 2 (OVN-mix 16 lbs/acre), Trt 3 (Low-Grow mix 16 lb/acre), Trt 4 (OVN-mix 22 lbs/acre), Trt 5 (Low-Grow mix 22 lbs/acre), and Trt 6 (Dutch clover at 16 lbs/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 this 2012 season. The 2011 established GC trials at Lamont’s were evaluated for soil coverage (GC coverage, weed coverage, and GC height). The plots at Mason’s were frost-seeded in March, 2012, to try to improve stand establishment.

Treatments were randomized and replicated, 3 plots 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 this season. The first treatments applied were 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. All other treatments were 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. The % weed cover was evaluated in each plot taking 3 readings per plot at 2-3 week intervals, and an average % 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. 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 until a post-emergent herbicide was necessary. We also recorded the total number of applications for the season for future economic analysis. Treatments lists are attached.

We measured the tree trunk radius 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. We examined the trunks of the trees looking for any bark damage that was visible – no damage was detected.

We collected soil health core samples and sent them to the Cornell Soil Health Lab for various soil parameters including nutrients. We also tried some water infiltration tests to determine the porosity of the soil and look for any differences in potential runoff for some of the treatments.

A grower identified a new orchard site for planting in 2013. The field was planted in corn in 2012. We walked the field using GPS and 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 has been harvested, sub-soiled, plowed and disked and is ready for planting in the spring. We will walk the new planting with the weed map to identify the perennial weeds that survived the treatment.

We also evaluated perennial weed control in herbicide plots at Lamont’s and Mason’s.

• Herbicide Treatments and Dates Applied

Impacts and Contributions/Outcomes

2012 main findings: (1) Dutch clover germinated and established more quickly than both grass mixes at the GC Fowler site. It can become a weed problem in the in-row spacing. Clover spreading into the tree row has been difficult to control with herbicides, even glyphosate. However, it was the GC treatment that most impressed the grower by the end of the first year, (2) Both rates of the OVN-Mix continued covering the soil and competing against weeds better than the Low-Grow mixes at the GC Lamont site, (3) Clover soil coverage was the lowest and the most weedy by the end of the second growing season at the GC Lamont site, (4) OVN-mixes (both rates) covered the soil better than the Low-Grow mixes by the end of the first growing season at the GC Fowler site, and (5) weed control suppression was maximum with the Dutch clover treatment at the GC Fowler site.

1. No herbicide program in these plots gave season long control.
   Prowl or Surflan alone will provide about 30-40 days of weed control, higher rate, the longer control.
   Adding Chateau (12 oz./acre) or Goaltender to Prowl or Surflan will extend effective control and broaden spectrum of control
   Matrix at 4 oz./acre provided long term control, 60-90 days in 1-yr trees
   Alion will provide 75 days control in trees 3 years or older.
   The Alion plots at Mason’s were the only plots that did not have winter annuals growing in the early spring resulting in the lowest seasonal average percent weed cover.
   Sinbar residual was variable – 40-87 days
   Diuron + simazine (low rates) cheapest but watch for resistant weeds
   Irrigation will reduce the residual herbicide effect.

1. There was a significant reduction in tree growth in the new planting if left weedy. But there was less difference in tree growth in 1-yr established trees. Therefore, newly planted trees are most sensitive to weed competition.
   The reduction in tree growth, measured by trunk cross-sectional area, will impact on the following season’s capacity to carry fruit. Crop load is adjusted to 4-6 apples per cm2 of TCSA. This will translate into reduced profitability and slower payback on establishment costs!
   After 2 years, the potential crop value in the herbicide treatments that resulted in the greatest tree growth was increased by $2300 per acre in the super spindle planting, and $1200 per acre in tall spindle plantings compared to the weedy untreated plots.

To date, there are no significant differences in soil nutrient level or pH. Results from the soil health tests will follow.

No evaluation results have been analyzed to date. Will follow up in spring of 2013.

• Ground Cover Establishment Evaluation Results
• Evaluation of Herbicide Treatments on Tree Growth
• Percent Weed Cover Results

Collaborators: