NOMINATING PARTY : The United States of America

DATE: APRIL 4 , 2013

BRIEF DESCRIPTIVE TI TLE : Response to questions from the U.S.G and M BTOC bilateral of April 3 , 2013 on strawberry fruit

SITE NAME (OPEN FIEL D): Strawberry Fruit

The USG thanks MBTOC for bringing to our attention the Zveibil (2012) and Noling and Cody (2012b) studies for control of Macrophominia phaseolina

. While there is suggestive evidence that alternatives could meet the needs of California strawberry growers, the U.S. government believes that the considerations presented to you during our presentation on April 3, 1013 merit the present Critical Use Nomination for 2015 as prepared.

The California strawberry researchers have noted the metam

- sodium research work on Macrophominia from Florida and Israel (Noling and Cody 20 12 and Zv eibil 2012) and are planning dose response or rate finding studies this year with metam sodium. While the research work looks promising we would like to recommend caution in weighing these studies because there is an extensive body of research that demonstrates that metam

- sodium is not effective under California conditions

.

The research of Zv eibil looked at the viability of Macrophomina based on buried sclerotia and strawberry stolons . The study did not look at crop yield or natural populations of Macrophominia in the soil. Without yield data it is hard to determine the season long control of the different treatments. The Macrophomina research in Florida by Noling and Cody in 2012 had the number of dead plants/40 foot of row it did not have yield data. Without yield data it is hard to determine the season long control of the different treatments. In addition, the treatments with Telone C

- 35 showed statistically s imilar number of dead plants compared to methyl bromide:chloropicrin while we know that under field conditions in California th e Telone C

- 35 is treatment is not effective. In Florida

, a single cultivar

, ‘Festival

, ’ was tested in a single trial and it’s p athogen resistance is unknown under California conditions. The impact of California production practices, environmental conditions and cultivars is still unknown when comparing these treatments.

R esearch in California suggests that metam

- sodium may no t be effective under local conditions. H. Ajwa (personal communication April 3, 2012) stated “In our experiments, we need over 630 lbs/ac of Na

- methyldithiocarbamate to control Macrophomina phaseolina. This is equivalent to 150 gal/ac of metam sodium ( 1 gal of metam

- Na contains 4.22 lbs a.i). These results are from laboratory dose

- response experiments using infested plant materials placed in 250 g soil in closed jars over 24 hours at 22 o C. The actual LC90 was over 4300 umol a.i/kg soil.” This U.S. g overnment would like to point out that this rate is almost twice the legal maximum rate of 350 lb ai/acre allowed in the U.S.

Earlier research indicated that metam

- sodium did not provide consistent efficacious control under California conditions . Ajwa and Trout (2004) published work showing that drip appliedmetam

- sodium did not provide strawberry fruit yield equivalent to MeBr:chloropicrin. “The

market yield from the Vapam HL [metam

- sodium] treatments relative to MB:CP [67:33] treatment range d between 67% to 86% in Watsonville and between 78% to 99% in Salinas.” However, disease in Salinas was very low (<2%); Watsonville had varying incidences of Verticillium depending on season (out of 3 seasons). For this study (2004 was prior to the “emer gence” of Macrophomina in California) the authors conclude that “In our studies, the simultaneous drip application of Vapam HL and InLine or CP EC in years 1 and 2 did not control verticillium wilt in the severely infested Watsonville soil.” The summary b y Nelson et al (2000) showed that bedtop applications of metam

- sodium were not effective. Shaw and Larson (1999) also summarized data to demonstrate that metam

- sodium was not effective.

The U.S. is planning further work to test the efficacy of metam

- sodi um on Macrophomina under California conditions. We also plan to gather data on efficacy of the high rate of chloropicrin under TIF and its ability to control Macrophomina, Fusarium and Verticillium in commercial field applications over time on California strawberries and will apprise MBTOC of its findings

. A s you know, regulatory uncertainty is another challenge. County Agricultural Commissioners in California will need to render their opinion on whether these high rates of straight chloropicrin can be us ed safely without harm to workers and by

- standers. Future regulatory requirements by the California Department of Pesticide Regulation (CDPR) for chloropicrin add further to our uncertainty. As stated yesterday, CDPR may also change Telone's regulations.

CITATIONS Ajwa, H. and T. Trout. 2004. Drip application of alternative fumigants to methyl bromide for strawberry production. HortSci 39(7):1707

- 1715. Accessed online on April 4, 2013 at http://hortsci.ashspublications.org/content/39/ 7/1707.full.pdf

Nelson, M. B. Olsen, B. Johnson, and J. Norton. 2000. Results from 1999

- 2000 USDA IR

- 4 Trials MBA Field Trials in CA and FL strawberries. Accessed online on April 4, 2013 at http://www.m

bao.org/altmet00/3nelson.pdf

Noling, J. W. and Cody, M. 2012. USDA ARS South Atlantic Areawide Project: Large scale field demonstrations demonstrations in Florida strawberry 2011

- 12. Annual International Research Conference on Methyl Bromide Alternatives and Emissions Reductions (2012). http://mbao.org/2012/Proceedings/27NolingJ%20AreaWide%202012.pdf

Shaw, D.V. and K.D. Larson 1999. A meta

- analysis of strawberry yield respo nse to preplant soil fumigation with combinations of methyl bromide

- chloropicrin and four alternative systems. HortSci. 34(5): 839

- 845. Accessed online on April 4, 2013 at http:/ /hortsci.ashspublications.org/content/34/5/839.full.pdf

Zveibil, A., Mor, N., Gnayem, N., and Freeman, S. 2012. Survival, Host

- Pathogen Interaction, and Management of Macrophomina phaseolina on strawberry in Israel. Plant Disease 96:265

- 272. http://www.apsnet.org/publications/plantdisease/2012/February/Pages/96_2_265.aspx (link is to abstract only).