Proposed EPA Labels Changes Could Impact Desert Crops 2015
The U.S. Environmental Protection Agency (EPA) recently proposed additional mandatory pesticide label restrictions that would prohibit the application of acutely toxic pesticides during the time crops are in bloom and commercial bees have been placed in or near fields for pollination services. If these proposed label changes are implemented they could have important implications for managing key pests on desert crops which require the use of contracted bees for pollination. Specifically, the proposed labelling reads as follows: “Foliar application of this product is prohibited from onset of flowering until flowering is complete when bees are on-site under contract”. This label would apply to pesticides that have an acute contact toxicity value less than 11 micrograms per bee (LD50<11 μg/bee). Unfortunately for desert producers, the list of acutely toxic insecticides includes all of the pyrethroid, organophosphate, carbamate and neonicotinoid insecticide active ingredients currently used for control of major pests. Also included in this list are Exirel, Radiant, Success, Sequoia, Abamectin, Proclaim, Avaunt and Torac. Even insecticides approved for organic production are not exempt, as azadirachtin (e.g., Aza-Direct), pyethrins (e.g., Pyganic), spinosad (Entrust) and rotenone are also on the restricted list. The full description of the proposed label changes, including the list of acutely toxic pesticides (Appendix A) affected and proposed label language (Appendix B), can be found here: EPA’s Proposal to Mitigate Exposure to Bees from Acutely Toxic Pesticide Products In my view, fall melons would be most directly affected by this proposed label change. Economic production of fall melons requires pollination services, but of course also requires adult whitefly control during the bloom/pollination period to suppress the spread of virus (CYSDV). Based on EPAs proposed label restrictions, application of industry standards like Assail, bifenthrin, fenpropathrin, and Exirel would not be allowed anytime, day or night, on fall melons as long as commercial bee hives are present. This could make whitefly/CYSDV control during bloom very difficult. UA research has clearly shown that the remaining alternatives labeled for whitefly control not on EPAs proposed list (i.e., Knack, Vetica, Oberon, Coragen, Fulfill, Beleaf) have little effect on preventing virus infection. Under this scenario, spread of CYSDV in some fields could essentially go unchecked for several weeks. If you are interested in voicing your opinion on this new proposal, EPA is currently accepting public comments until July 29, 2015. For more information on how to submit comments go to: http://www2.epa.gov/pollinator-protection/proposal-protect-bees-acutely-toxic-pesticides and http://www.regulations.gov/#!docketDetail;D=EPA-HQ-OPP-2014-0818.
This study was conducted at the Yuma Valley Agricultural Center. The soil was a silty clay loam (7-56-37 sand-silt-clay, pH 7.2, O.M. 0.7%). Spinach ‘Revere’ was seeded, then sprinkler-irrigated to germinate seed Jan 18, 2024 on beds with 84 in. between bed centers and containing 30 lines of seed per bed. All irrigation water was supplied by sprinkler irrigation. Treatments were replicated four times in a randomized complete block design. Replicate plots consisted of 15 ft lengths of bed separated by 3 ft lengths of nontreated bed. Treatments were applied with a CO2backpack sprayer that delivered 50 gal/acre at 40 psi to flat-fan nozzles.
Month
Max
Min
Average
Rainfall
January
68
42
54
1.14 in
February
73
47
59
0.50 in
March
77
50
63
0.31 in
Downy mildew (caused by Peronospora farinosa f. sp. spinaciae) was first observed in plots on Feb 19 and final reading was taken on February 26, 2024. Spray date for each treatments are listed in excel file with the results. Disease severity was recorded by determining the percentage of infected leaves present within three 1-ft2 areas within each of the four replicate plots per treatment. The number of spinach leaves in a 1-ft2 area of bed was approximately 144.
The data (found in the accompanying Excel file) illustrate the degree of disease reduction obtained by applications of the various tested fungicides. Products that provided effective control against the disease include Orondis ultra, Thrive 4 M, Fungout, Cevya, Eject and Zampro. No phytotoxicity was observed in any of the treatments in this trial.
Controlling Disease and Weeds with Band-Steam – Yuma Trials Show Good Promise
In previous articles (Vol. 11 (13), Vol. 11 (20), Vol. 11(24)), I’ve discussed using band-steam to control plant diseases and weeds. Band-steaming is where steam is used to heat narrow strips of soil to temperature levels sufficient to kill soilborne pathogens and weed seed (>140 °F for > 20 minutes). The concept is showing good promise. This past season, three trials were conducted examining the efficacy of using steam for disease and weed control in Yuma, AZ. In the studies, steam was applied in a 4-inch-wide by 2-inch-deep band of soil centered on the seedline using a prototype band-steam applicator (Fig.1). The band-steam applicator is principally comprised of a 35 BHP steam generator mounted on top of an elongated bed shaper. The apparatus applies steam via shank injection and from cone shaped ports on top of the bed shaper.
Trial results were very encouraging as the prototype applicator was able to raise soil temperatures to target levels (140°F for >20 minutes) at viable travels speeds of 0.75 mph. Steam provided better than 80% weed control and significantly lowered hand weeding time by more than 2 hours per acre (Table 1). Results also showed that Fusarium colony forming units (CFU) were reduced from 2,600 in the control to 155 in the 0.75 mph and 53 in the 0.5 mph treatments, respectively (a more than 15-fold reduction). A significant difference in Fusarium wilt of lettuce disease incidence was not found, however disease infection at the field site was low (< 2%) and differences were not expected. At 0.5 mph, fuel costs were calculated to be $238/acre which was considered reasonable and consistent with the values reported by Fennimore et al. (2014).
An unexpected finding was that plants in steam treated plots appeared to be healthier and more vigorous than untreated plots (Fig. 2). This trial is still in progress and it will be interesting to see if this improved early growth translates into increases in crop yield.
In summary, early trial results are showing good promise for use of band-steam as a non-herbicidal method of pest control. We plan on conducting further trials in this multi-year study. If you are interested in evaluating the device on your farm and being part of the study please contact me. We are particularly interested in fields with a known history of Fusarium wilt of lettuce and/or Sclerotinia lettuce drop that will be planted to iceberg or romaine lettuce.
As always, if you are interested in seeing the machine operate or would like more information, please feel free to contact me.
Acknowledgements
This work is supported by Crop Protection and Pest Management grant no. 2017-70006-27273/project accession no. 1014065 from the USDA National Institute of Food and Agriculture, the Arizona Specialty Crop Block Grant Program and the Arizona Iceberg Lettuce Research Council. We greatly appreciate their support. 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.
A special thank you is extended to Mellon Farms for allowing us to conduct this research on their farm.
References
Fennimore, S.A., Martin, F.N., Miller, T.C., Broome, J.C., Dorn, N. and Greene, I. 2014. Evaluation of a mobile steam applicator for soil disinfestation in California strawberry. HortScience 49(12):1542-1549.
Click link below or picture to see the band-steam and co-product applicator in action!
Carryover of Vegetable Herbicides to Wheat Grown in Rotation
Almost all the herbicides used on lettuce, cole crops and melons have restrictions on how soon wheat can be planted in rotation after they have been used. Experience has demonstrated, however, that safe intervals can vary considerably based upon many factors and are almost always much longer than they need to be. The most important factors are rate applied, irrigation practices and tillage. For example, when Kerb used to be banded at 2 to 4 lbs. per acre after planting and incorporated with furrow irrigation, it was common to see treated strips across wheat fields which followed. This is uncommon now that lower rates are Chemigated. We still see some Balan injury at ends of fields or in overlaps especially when sudan is planted. Wheat it not very sensitive to Prefar and carryover injury is uncommon.