Fungicide field study

Uncertainty may also affect the credibility of ecological risk assessment procedures. In the late 1970s, the USEPA presented a risk assessment for the use of granular carbofuran on com, including a detailed list of field studies and incidents. The Eederal Insecticide, Fungicide, and Rodenticide Act Science Advisory Panel concluded there was insufficient information to justify restricted use labeling and recommended further testing. Nearly 20 years later, the accumulation of additional field studies and incidents provided sufficient evidence such that approvals for use of carbofuran were withdrawn. 

The total number of berries with fruit rot symptoms and the number of berries with symptoms of anthracnose or stem end rot from the April 24 harvest time were significantly lower from plots treated with the fungicides Switch, Cabrio , CaptEvate , and Pristine than from those receiving no fungicide treatment (Table 2). The most prevalent diseases in the Louisiana field study were anthracnose caused... 

The discovery of brassinolide by scientists at USDA led to the development of a new group of plant growth substances, termed brassinosteroids, which have the potential for increasing crop yields and biomass. The chapter summarizes the USDA s contributions to brassinosteroids, which include isolation and identification of brassinolide, synthesis of brassinolide and its analogs, and limited biological and field studies on brassinosteroids. An overview of the current data requirements for the registration of brassinosteroids as biochemical pesticides under the Federal Insecticide, Fungicide, and Rodenticide Act is presented. 

V. Anticipate the Impact of New Candidate Fungicides on Resistance Problems. The methods (especially field studies) for evaluating resistance potential of new compounds must be improved and used. 

The purpose of this presentation Is to describe the results of field studies of dermal and Inhalation exposure of applicators and mixer-loaders to the fungicide mancozeb (DITHANE M-45 fungicide, 80Z active Ingredient wettable powder, a product of Rohm and Haas Company, Philadelphia, PA 19105, was used In these studies), a coordination product of zinc Ion and manganese ethyleneblsdlthlo-carbamate, and ethylene thiourea (ETU). The latter compound Is a decomposition product of all EBDC s (mancozeb, maneb, metlram, nabam and zlneb) and also Is produced from EBDC s as an artifact of the analytical procedure for ETU. 

A series of novel 4-phenoxyquinolines has been developed which show potent control of fungicide-sensitive and resistant strains of powdery mildew in grape and cereal crops. Protective, curative, and systemic activity has been observed for these materials, which also control other fungi. Strong activity in field studies has been noted and no crossresistance was encountered when fungicide-resistant strains of mildew were treated with these compounds, thereby suggesting a novel mode of action. The discovery, synthesis and structure-activity relationship of this novel class of fungicides are presented, as well as some data from field and cross-resistance studies. 

J.H. Massey and S.K. Singles, Photostability of two fungicides on spray application monitors, in Terrestrial Field Dissipation Studies Design, Interpretation and Purpose, ed. E.L. Arthur, V.E. Clay, and A. Barefoot, ACS Symposium Series No. 842, American Chemical Society, Washington, DC (2003). 

Field Evaluation Studies for Cytolytic/Fungicidal Substances (26). 

C-labelled active plant protection substances for 13 years (17, 18). The results indicate that intensive cooperation between plant protection chemists, phytopathologists, phytophysiologists and specialists in the radioisotope techniques is necessary to fully exploit the application possibilities and to interpret the results. The special experimental facilities at the JUlich Nuclear Research Center which include practically oriented field tests supplemented by detailed studies under defined climatic conditions enable practical and relevant results to be obtained (17-19). The aim of this contribution is to provide new insights and information on the system effectiveness and residue behavior of azole fungicides. 

At about the same time, the first information was received about product failure after continuous and exclusive use. The investigation of the pathogen populations of such fields yielded highly resistant strains (28, 29, 40), whereas so far no field resistance has been reported for cymoxanil or fosetyl. Thus, in contrast to the favorable results of a broad range of model studies, resistance had appeared very fast under field conditions. The lesson to be learned from this experience is that results of model studies have to be used with caution. Model studies must include the use of chemical mutagens and highly active, systemic fungicides should be used as if a risk of resistance exists until their mode of action is known. 

Detached leaf assays provide us with the opportunity to evaluate new fungicides directly on the leaf surface in a dose-response format (Table 1). This assay allowed us to benchmark potential lead compounds such as CAY-1 and sampangine with a commercial standard (azoxystrobin) of known mode of action (Qo I inhibitor). The number of diseased lesions was used to determine effective concentrations needed for disease control. Lesion size is used to determine the relative effectiveness of the systemic activity that produced curative activity 24 hrs after inoculation. The detached leaf assay was also used to establish experimental field rates for future studies. Study of protectant activity indicated that 1250 ppm. CAY-1 or sampangine appeared to be an effective concentration for disease control of anthracnose on the leaf surface, or between 100-1000 times the concentration required for in vitro activity (Post, Table 1). 

Resistance has not thus far been a serious problem for the EBI s. Although numerous resistant mutants have been developed in laboratory studies, resistance problems in the field have not occurred. However, recent investigations related to the use of a triazole fungicide on barley indicate that resistant strains of pathogenic fungi may be increasing (26). The fact that there have not been major problems may be associated with the nature of the mode of action and the fact that mutants appear to have reduced fitness (11, 18). In other words, the genetic alterations conducive to survival in the presence of these compounds may also reduce fitness. 

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