Research Report
to the California Pepper Commission
Title: Garden Symphylan Management
Funding Period: March 1, 2005 – February 28, 2006
Principal Investigator:
William E. Chaney
U.C. Cooperative Extension – Monterey County
1432 Abbott Street
Salinas, CA 93901
Objectives:
- To test registered and potential pesticides for control of the garden symphylan in field trials in direct seeded peppers
- To test registered and potential pesticides for control of the garden symphylan in field trials in transplanted peppers
Summary: Work on all soil-borne pests is challenging, largely because it must be done preventatively, sampling is difficult, and pest populations are very difficult to predict. This is true of symphylans as well, although we have a good sampling procedure, and we expected problems to occur in the same areas of the same fields year after year. The latter is proving to be less true than we as researchers would like, while still more true than growers would prefer. During this period we examined many fields where pepper growers (or their PCAs) felt their might be a problem, with no success. In light of this, we used a different tactic, namely to transplant into an existing symphylan hotspot. This does provide useful data and directions for further research, but does not reflect production pepper conditions and does not allow for direct seed pepper work. The only trial with direct seeded peppers turned out not to have symphylans at all, and did not suffer any apparent damage.
Trial Results
Procedures: This trial was conducted in a grower cooperator field near San Juan Baustista, CA with a history of symphylan pressure to achieve a good evaluation of the performance of the test materials. The design was a randomized complete block with four replications. All materials were applied as a transplant drench, where the transplants were dipped into the test material at a 60 gal/Acre equivalent. The treated transplants were then hand planted on March 17, 2005 into the grower field and watered in. Subsequent irrigation of the trial occurred with movable set sprinklers, to adequately irrigate the field crop (lettuce).
The products were evaluated two ways by measuring the pest population using raw potato bait stations, and by weighing the above ground portion of the plant. A bait station is made by scraping away the dry soil on the surface to expose moist soil pores, placing a freshly cut slice of potato on the surface, and covering with a white plastic pot. Stations are evaluated 24-72 hours later by quickly removing the pot and counting the organisms on the soil surface and then those clinging to the potato.
Materials: The materials tested were: Diazinon 4E 2 pints, Capture 2EC 6.4 fl oz, Mustang Max .8 EC 4.3 fl oz, Metasystox R 2 pints. Baythroid 2 EC 3.2 fl oz all given at a per acre rate.
Results: The bait station sampling showed very little symphylan activity, untreated control less than 1 per station, but some differences between treatments.
Treated and Transplanted March 17, 2005 near San Juan Bautista
Plant weights showed greater differences between treatments, especially for the transplanted lettuce.
Treated and Transplanted March 17, 2005 near San Juan Bautista
Discussion: The weather was too cool for the peppers in March to grow well and the differences in plant weight from 14 days after planting to 39 days after planting were minimal. The trial could not continue as the growers had harvested the crop and turned the field around. The application method, drenching the transplant into the test material, is not currently labeled, but does show that the plants treated with the materials tested when placed at the critical site, at the emerging roothairs, were significantly larger and grew more compared to the untreated control. Further research is needed to determine methods to apply these materials in compliance with current label restrictions to achieve comparable efficacy.
Procedure: This trial was conducted in a grower cooperator field near Gilroy, CA with a history of symphylan pressure. The design was a randomized complete block with four replications. Materials were applied by opening a furrow, spraying the test material on the soil at a 60 gal/Acre equivalent, closing the furrow, and transplanting peppers in. The experimental transplants went in at the same as the field was planted, April 20, 2005.
The products were evaluated two ways by measuring the pest population using raw potato bait stations, and by weighing the above ground portion of the plant.
Materials: The materials tested were: Diazinon 4E 2 pts, Mustang Max 4.3 oz, Warrior .1 LB AI 12.8oz, Admire 24 oz, Regent (fipronil) 3.2 fl oz, Vydate 4 pints, in 60 gallon/acre dilution equivalent and compared to an untreated control.
Results: The bait station sampling showed modest symphylan activity, with the untreated control about 4 per station, and some differences between treatments.
Treated and Planted on April 20, 2005 near Gilroy
Plant weight showed a three-fold difference between the untreated control and Warrior.
Treated and Planted on April 20, 2005 near Gilroy
Discussion: Differences in symphylan activity seen at 34 days after treatment (DAT) was much less dramatic at 62 DAT. The earlier symphylan activity appears inversely related to plant weight at 61 DAT. Warrior and Mustang Max stand out as effective at increasing plant weight, and to a lesser degree these materials repelled symphylans from the bait stations.
This trial was oversprayed prior to planting on beds 1-4. The grower had treated the test plot prior to the trial with a tank mix, which included an organophosphate and a pyrethroid. The oversprayed area could be distinguished from the rest of the trial by increased plant vigor and the reduction of symphylans on the bait stations. This effect was additive to the trial treatments and our overall results were consistent with previous trials.
Treated and Planted on April 20, 2005 near Gilroy
The table below shows the arrangement of the test treatments; the shaded area was oversprayed.
| Bed Number | |||||||
| Treatment | 1 | 2 | 3 | 4 | 5 | 6 | 7 |
| Regent | Untreated | Warrior | Diazinon | Mustang Max | Admire | Vydate | |
| Mustang Max | Admire | Vydate | Untreated | Warrior | Diazinon | Regent | |
| Admire | Mustang Max | Warrior | Vydate | Untreated | Regent | Diazinon | |
| Mustang Max | Regent | Diazinon | Warrior | Untreated | Admire | Vydate | |
Procedures: This trial was conducted in a grower cooperator field with a history of symphylan pressure near King City. The design was a randomized complete block with four replications. Blocks were one bed wide and reps were 25 ft long. All materials were applied to the bed top on April 22, 2005 with a backpack; carbon dioxide pressurized sprayer and incorporated with a tiller. Peppers were seeded with a Plant-It Jr. The field was sprinkler irrigated. The performance of the products was evaluated by measuring the pest population using raw potato bait stations.
Materials: The materials tested were: Diazinon 4E 2 pts, Mustang Max 4.3 oz, Warrior 12.8oz, Admire 24 oz, Regent (fipronil) 3.2 fl oz, and Vydate 4 pints.
Results: The pest organism found at the site was not symphylans, but instead the seed springtail (Onychiurus pseudarmatus). Damage to seedlings occurs in the same way as symphylans, both these pests, damage to roothairs, which inhibits stand establishment. The materials were evaluated at 28 days after treatment (DAT). The flowing graph presents the results as the mean number of springtails per bait station over the four replicates.
Treated and Planted April 22, 2005 near King City CA
Discussion: No differences in the plant size or mortality were observed despite a history of problems reported by the grower. The results present here and others we have obtained seem to indicate that candidate materials for springtail management may exist, but the methods for application and incorporation must be further refined.