It is widely accepted that cotton yield will be negatively affected if seedlings succumb to soil-borne pathogens such as Rhizoctonia solani and Pythium species. Seedling diseases were estimated to have caused an average yield loss of 3.2% from 1992-20019 amounting to an economic loss of $242 million.24 With this understanding, the standard approach to cotton disease management involves implementing practices that protect the developing cotton seedling, including planting on raised seedbeds, and planting when moisture and temperature conditions are favorable for germination and emergence of cotton.83,75
It is of course impossible to guarantee optimal environmental conditions during and after planting. The focus of SSP disease management research has therefore focused on factors that are under grower control, including: selection of disease resistant varieties, use of treated seed, applying in-furrow fungicides, crop rotation, and using seed with good cool germination values. To learn more about adoption of these practices, we presented growers with a list of disease management tactics and asked how frequently they use each one. Growers responded to each item by circling a number from 0 (never) to 3 (always).
Figure L shows the proportion of growers who indicate they use disease management tactics studied with SSP funding, either often or always.
Figure L - Use of Disease Management Tactics
Nearly three quarters of respondents (74.9%) practice crop rotation to limit disease pressure and about the same proportion (74.8%) often or always select cotton varieties with known resistance to diseases. Fungicide-treated seed was also highly relied upon (72.3%). Selecting seed with a high cool germ value was frequently used (58.2%). Less than half of respondents (41.2%) employed in-furrow fungicide treatments.
As described earlier, not all practices asked about in this or other questions have been the subject of SSP research. Regarding disease management, this appears to be appropriate given that growers clearly understand the value of practices that help get the crop off to a good start. Specifically, 93.5% of respondents often or always plant with adequate soil moisture. Planting when the 4” depth soil temperature is 65° and when predicted weather is warm/dry is the standard approach used by 88.2% and 88.4% respectively. In addition, almost half (49.8%) plant seeds on beds. It is clear, then, that most growers at least try to implement strategies that are favorable for crop germination and emergence.
There was only modest use of in-furrow fungicide treatments. While such treatments were found to improve stands, positive outcomes were contingent on a variety of other factors (severe disease pressure, soil temperatures below 60° F, and when rain might occur within three days of planting29 ). In another study, in-furrow fungicide treatments resulted in net returns of $46.28 per acre higher than the commercial on-seed treated plots.89 However, there is contrary evidence that in-furrow treatments do not add any further improvement to pre-treated seed.83 The somewhat limited use of in-furrow treatments may reflect these inconsistent results, satisfaction with protection already afforded by pre-treated seeds, genetically-based disease resistance and crop rotation, or the fact that disease incidence still depends on climate factors.
Given the high extent of adoption of SSP research topics in the area of disease management, we conclude that growers understand the benefits of the various management options currently in widespread use.