Anaerobic Soil Disinfestation as Pre-plant Treatment for Perennial Strawberry in the Northeast

Trials were established on four farms in the spring of 2021, one in Western NY, two in Eastern NY and one in Maine. The two Eastern NY locations were established as matted row strawberry systems and the Western NY and Maine locations were established on black plastic mulch.

 May 26 –Underhill Farm, Western NY; May 26 –Six Rivers Farm, Maine

Strawberries were ordered and sourced from Nourse Farms in South Deerfield Mass.  Jewel was used on both Eastern NY farms.  Cavendish was used on Maine farm and Galletta was used in Western NY.

As strawberry plants were received, sub-samples were sent to Dr. Kerik Cox for evaluation of disease and other potential issues arriving on the plants from the nursery. 

Treatments include:

• Control
• Brassica Seed Meal @ 4.5 Tons/acre - all 4 farms
• Alfalfa Seed Meal @ 9 Tons/acre - all 4 farms
• Dried Molasses @ 9 Tons/acre - all 4 farms
• Ridomil Drench (Western NY location only) - growers rate 
• Grower Standard Fumigant (one Eastern NY location only) - applied the fall before
• Mustard Cover Crop Biofumigant (one Eastern NY location only) - seeding rate?

In Eastern NY, the two trial locations were plowed and disked in preparation for the trial by the farmers. After this, soil samples were taken and sent to the Cornell Soil Health Testing Laboratory for Comprehensive Assessment of Soil Health. CSHT sample dates were: May 20, 2021 –Ariel Farm, Saratoga County, NY; May 21 –Hand Farm, Washington County, NY.  On May 24 and 25, the treatment materials were applied to the trial in repeated randomized plots of 50' lengths in amounts specific to each treatment. The farmers disked in the treatments and drip tape was laid and turned on. Silage tarps were laid over the entire trial area and secured with weights. The silage tarps were left in place until temperatures under the plastic reached a minimum of 100 degrees. For the mustard biofumigant treatment, the seed was sown on May 25 and irrigated. The tarps were removed on June 17 and the plots were left to off-gas. On June 23, Jewel bare root strawberries were planted into the treatment plots, one farm using a strawberry planter set at 18 inches in row and one farm by hand at 20 inches in row. For the mustard biofumigant treatment, the crop was terminated and incorporated by rototilling at the slowest speed on July 2nd and left to decompose. The bare root strawberries were planted by hand on July 8th. Weed evaluations were done on August 10th, counting the number of broadleaf and grass weeds in 3 square feet twice in each plot and identifying specific species as well as a visual disease evaluation. Plant samples were collected in early September and send to Dr. Kerik Cox for evaluation of disease and other issues in the first growing season. 

Photo 1: Treatments applied 
Source: Natasha Field

Silage tarps laid. Source: Natasha Field

In Western NY, the treatments were laid out on May 26, with the grower covering the treatments with black plastic mulch and irrigating. After three weeks or so, the holes were poked in the plastic to let the treatments off-gas and bare root strawberries were planted in by the grower. In the first year of the ASD trial at Underhill, we evaluated 3 ASD carbon sources (brassica seed meal, molasses, alfalfa seed meal) against a positive control (Ridomil Gold SL soil drip) and a negative control (no treatment). All plots were grown as plasticulture, June-bearing strawberries 'Galletta." Initially, strawberries in the ASD treatments appeared to have some nutrition issues and had small, chlorotic leaves. By mid-summer they grew out of this and had green leaves. Weeds were an issue in this planting, and the ASD didn't seem to do much to prevent weed issues. 

Plant health was evaluated twice in the growing season. In both evaluations, Ridomil Gold SL-treated plots had the most healthy plants, but this may have been compounded by the positioning of the Ridomil Gold treatment-- on the border of the field, where weed pressure was reduced due to neighboring plots. On the second plant health evaluation, plant health declined across all treatments. Alfalfa seed meal was the second-best treatment, after Ridomil Gold. While brassicas have a track record of improving soil health as a cover crop, using them as an ASD carbon source did not seem to provide good results-- the plant health in those treatments was worse than the negative control that receives no treatment.

As for the grower, his opinion of Ridomil Gold is very high, although he is interested in sustainable means to prepare soil for strawberries. In a different strawberry planting, he used Ridomil Gold in the autumn, and those fields looked really good. I am hoping we'll see more positives from the ASD treatments as we can collect more comprehensive data next year. 

Strawberry plants in first year of growth. Source: Anya Osatuke

2022 Growing Season Data Collection Summary

• Assess plants vigor after pulling back the mulch (April)

• Weed Assessment – should be done before renovation – during harvest preferred. Within 6 square foot grid, count weeds, classify them as grass or broadleaf and identify them as best you can. Do this in each rep.  We are not harvesting the weeds.
• During harvest –
  1. fruit assessments
     1. Fruit ‘type’- pick 4 fully ripe, primary fruit from each replication of each treatment.  Don’t pick cat-faced, obviously misshapen berries.  You need good looking berries for this one.  using the descriptions provided (see attached), give them a Yes or No ranking for typiness and size.  This is somewhat subjective, but if they fall within the basic parameters of size, shape and color – then it’s a YES.  If they are completely wrong looking – like they are orange rather than red when fully ripe, or all very round when should be conic – then put them in the NO category. 
     2. Fruit Size - Using those same 4 fruit from each rep – measure width, length and weigh the berries

• Fruit Brix - Using refractometer, measure brix of berry juice from berries collected

1. Subjective flavor rating

• Miscellaneous observations

1. Note observations of pest problems – insect and disease – during harvest
2. Note the start date of commercial harvest in the plots and if they differ from one another. 
3. Note harvest duration (end of picking date).

• After renovation – foliar nutrient analysis. 
  1. Collect 10-12 full trifoliate leaves from each replication.  Combine the reps for each treatment and send in leaves for all 4 treatments plus additional treatment if you have one. Rinse quickly with distilled water and spin dry or let air dry.  The leaves should be put in paper bags to ship. 
• Visual plant assessment – 1-4 rating for each plant in each rep. This was done when foliar samples were gathered in early to mid-August. 
• Destructive plant samples for Kerik in mid-August to early September. 
  1. Please pull 3 plant samples from each rep. Just the plant, not all of the rooted runners.  As much of root system as possible should be removed with each plant.  Soil should be gently shaken off, then put the root zone into a plastic bag with foliage peaking out of the top.  Refrigerate unless you can ship them immediately.  If it’s very hot and dry, you can put a barely damp paper towel around the roots inside the plastic bag.  Ship with a cold pack if you can. 
• Soil health sample should be pulled in late September or early October.
  1. Pull Soil Health test samples and submit to Cornell lab – We are using the Standard PLUS sample at $130/sample. For each farm gather 1 sample for each of the 4 treatments.  For more information and instructions on soil sampling protocol see https://soilhealth.cals.cornell.edu/testing-services/comprehensive-soil-health-assessment/ 

In addition to the field data collected, Elizabeth Higgins has been working with growers to determine their average cost of production.  We have been collecting cost of treatments and she will assemble the change in cost of production for treatments in a report.