Insect, Disease, and Weed Managment

INSECTS: Insect problems have generally diminished over time. Aphids and Lepidopteran pests (especially, peach tree twig borer and oriental fruit moth) have decreased over time at Woodleaf farm. Bt was applied in the early 1990s for peach tree twig borer and oriental fruit moth, but has not been used since the 1990s. Thrips have been a problem at Woodleaf, but damage has decreased since Carl began to manage his ground covers to provide habitat for predators and parasites of insect pests. Carl manages the mowing timing of his ground cover/living mulch and allows the ground cover to flower and seed in the orchard until harvest. The flowering ground cover provides food and habitat for predators and parasites who provide biological control of pests. In 2012 the only insect spray applied at woodleaf was a half spray (every other row middle) of a certified organic microbial material (Spinosad) for western flower thrips and Drosophila.

DISEASES: Disease problems and spraying for disease have decreased over time at Woodleaf farm. In the late 1980s and early 1990s, Woodleaf sprayed certified organic fungicides pre-bloom and during bloom (2-3 sprays) for brown rot and leaf curl on peaches. After his brown rot research (1992 through 1996), Carl began a new spray program utilizing a micro-nutrient mineral mix 1-3 times during bloom. His disease management system also includes management of the living mulch/perennial ground cover and attention to orchard hygiene (including removing diseased fruit/mummies as well as pruning timing and tree size).

WOODLEAF FARM DISEASE MANAGEMENT

DISEASE MANAGERMENT HISTORY: Disease problems and spraying for disease have decreased over time at Woodleaf farm.  Brown rot was the main issue, causing up to 30% damage to ripe fruit some years in the 1980s and early 1990s. In the late 1980s and into the late 1990s, Woodleaf sprayed copper pre-bloom for leaf curl and wettable sulfur (15-20 lbs. per acre) during bloom (2-4 sprays) for brown rot on peaches. In the late 1990s, Carl was concerned about a rise in soil copper levels. Hence, informed by his 1992-1995 brown rot research (see Experiment below), Carl began a new spray program in the mid-1990s, dropping copper and utilizing a mineral mix (including kelp, minerals, and micronized sulfur at 8 to 15 pounds/acre) 1-4 times during bloom, depending on precipitation (more sprays during wet springs).   Micronized sulfur, which is a standard practice material used by organic peach growers for brown rot management, is part of Woodleaf’s bloom spray mineral mix. However, sulfur is now used at a lower rate (8 lbs/acre in 2013, 10 lbs per acre in 2014) due to the greater efficacy of micronized sulfur (compared to the old wettable spray sulfur materials) and Woodleaf’s success with its mineral mix bloom sprays.

Brown rot bloom sprays in 2014 were a mix of: 10lbs. micronized sulfur, 10lbs. gypsum, 10lbs. Azomite, 10lbs. ferrous sulfate, 6lbs. sulfate of potash, 6lbs. manganese sulfate, 1.5lbs. Solubor, 1.5lbs. Maxi-crop, 1lb. Nutramin, 1lb. Activate and 4oz. Thermax 70 mixed with 300 gallons of water with constant good mechanical agitation.

The marketable peach crop in 2013 was 79% premium grade, 17% off-grade (lower price), and 4% lost to brown rot damage.

Woodleaf’s disease management system also includes managing the living mulch/perennial ground cover (mowing during wet/humid weather) and strict attention to orchard hygiene. Orchard hygiene includes: removing all diseased fruit/mummies as well as pruning timing, and a smaller, open tree size and shape. In three fields with deficient soil copper levels, Carl is considering spraying copper pre-bloom for brown rot in 2014 or 2015. Woodleaf still manages for Fireblight on apples and pears regularly at bloom, using Carl’s mineral mix, Seranade (Bacillus subtilis), and Blossom Protect (Aureobasidium pullulans). Peach leaf curl is treated every fall, using lime sulfur. Other diseases, such as powdery mildew on peaches and apples and apple scab have decreased or remained stable at approximately 5-10 % cosmetic damage annually over time. The micronized sulfur in Woodleaf’s 2-4 bloom sprays on apples and pears may be helping to manage apple scab and powdery mildew on apples. Apple scab is a disease that Woodleaf’s apple-growing neighbors spray for regularly throughout the growing season.

Experiment: Peach Brown Rot Control 1992-1995 (Organic Farming Research Foundation Grant # 92-26).  Two rows of a very Brown rot susceptible peach variety (O’Henry) were divided into three replicated sections and sprayed with 11 substances for brown rot suppression in 1992 and 10 substances in 1993 (see total list of tested substances below). The most successful treatments, resulting in the least brown rot and highest yields in the experiment plots were: dry kelp plus basalt rock (55% marketable fruit); dry kelp alone (42%); compost tea + pink mucoid yeast (Aureobasidium pullulans) (41%); and hydrogen peroxide + pink mucoid yeast (40%). These treatments out-performed the common practice organic disease controls, used alone at the following rates: copper (10 lbs. /acre) and sulfur (20 lbs. /acre).  The Aureobasidium pullulans yeast was found on the leaves of Woodleaf peach trees and cultured by Chuck Sellers.

In 1994 20 Royal Glo test trees were sprayed with the 4 substances that had performed best in 1992 and 1993, compared to a control of the standard practice sulfur treatment (three replicates of each spray treatment, with an unsprayed buffer tree between each sprayed tree). Test trees were sprayed four times during bloom and four times at weekly intervals before harvest with:

1.   Basalt rock dust at four lbs. per acre.

2.   Wilbur – Ellis Spray sulfur at 15 lbs. per acre.

3.   Aureobasidium Pullulans yeast (at 10 to the seventh power concentration) 1.5 gallons per tree.

4.   Algrow kelp at three lbs. per acre.

5.   A mixture of the rock dust, yeast and kelp.

Results were not statistically significant in 1994, but the basalt rock, kelp, and Aureobasidium Pullulans performed as well as the 15 pounds of sulfur. In 1995, the whole orchard received 8 mineral and kelp foliar sprays from just after bloom until harvest; foliar sprays consisted of: Hydrolyzed fish meal, Algrow kelp, basalt rock dust, Azomite, Soluble gypsum, corn calcium, apple cider vinegar, and sulfur. Before application of these 8 foliar sprays, at peach bloom, three spray treatments and a control plot of sulfur were compared on 12 Red Haven peach trees (three trees of each spray treatment).  All test trees were separated by an unsprayed buffer tree.  Four bloom sprays were applied every five to seven days from pink bud to petal fall to test the following materials:

1.   Basalt rock dust at four pounds per acre of dust.

2.   Wilbur – Ellis Spray sulfur at 20 lbs. per acre.

3.   Nutribiotic (grapefruitseed extract) at 1,000PPM

In 1995, the basalt rock dust trees yielded more than twice the control trees, with 2 1/2 times less brown rot.

Overall, from 1992 through 1995, the most successful treatments, resulting in the least brown rot and highest yields were mixtures of materials with rock dust, minerals (including sulfur), and kelp. These treatments out-performed common organic disease controls, normally used alone at the following rates: copper (8-16 lbs. /acre) or sulfur (15-20 lbs. /acre).  Both are standard practice for organic peach growers in California, however neither sulfur nor copper are recommended for brown rot control by university of California Extension or IPM programs (http://www.ipm.ucdavis.edu/PMG/r602100111.html#MANAGEMENT). Woodleaf now uses sulfur only as part of the bloom spray mix and at a lower rate of 8 – 10lbs. per acre. If there is a wet spring year Woodleaf will go as high as 15lbs per acre of sulfur during bloom.

The total list of substances tested at Woodleaf 1992-1995 included:

  • Kelp (dry and liquid)
  • Basalt rock plus dry and liquid kelp
  • Rado rock plus dry and liquid kelp
  • Compost tea #1 ((liquid kelp, molasses, basalt rock, and 10 gallons of finished compost)
  • Compost tea #2 (liquid kelp, molasses, basalt rock, and 10 gallons of finished compost/acre plus brewer’s malt and fish meal)
  • Compost tea plus pink mucoid yeast (Aureobasidium pullulans)
  • Hydrogen peroxide plus pink mucoid yeast (Aureobasidium pullulans)
  • Blend of basalt rock, dry kelp, hydrogen peroxide, compost tea, white wine vinegar, and pink mucoid yeast (Aureobasidium pullulans)
  • Azomite (montmorillonite clay) and liquid kelp
  • Copper 10 lbs. per acre.
  • Wettable sulfur 20 lbs. per acre
  • Citicidial grapefruit seed extract
  • Wine and raw apple cider mixed with water to a pH of 2.8 and applied at 300 gallons/acre
  • Irrigation water applied at 300 gallons/acre (control)

Thanks to Rodale Institute’s Your 2 Cents Fund and Western Sustainable Agriculture Research and Education who funded this project.

WEEDS: Handweeding and tractor cultivation has significantly decreased over time at Woodleaf. Mowing of living mulches has increased. Mowing to manage weeds/competition is also part of the disease, insect, and fertility management system. Timing of mowing the living mulch and the prunings (which are the “chipped branch wood” organic residue amendment part of the fertility management system) revolves around best timing for enhancing insect/disease biological control.

At Woodleaf Farm lots of flowering plants are left to go to flower to encourage beneficial habitat.
At Woodleaf Farm lots of flowering plants are left to go to flower to encourage beneficial habitat.

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Mowing is alternated between under the tree and the middle of the orchard rows to always have beneficial habitat close to the crop.
Mowing is alternated between under the tree and the middle of the orchard rows to always have beneficial habitat close to the crop.

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2 thoughts on “Insect, Disease, and Weed Managment

  1. THANKS FOR SHARING 30 Year experience, we are growing organic cacao trees and there are similar needs and answers. Congratulations!

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