To complete the objectives of the study, three field experiments will be conducted at three different locations each year representing multiple soil and environmental types present in Missouri. Experiments will be conducted as small-plot trials with each treatment replicated no less than 6 times. At each location, seven seed treatment combinations will be compared to a non-treated control. Examples of treatments include: a generic fungicide + insecticide base, the base treatment plus Aveo (Valent), the base treatment plus Nemastrike (Bayer), the base treatment plus Ilevo (BASF), and others. For all locations, a single SCN resistant variety will be used in order to remove the confounding effect of variety on seed treatment response.
Each plot will measure 10 feet wide by 30 feet long and 10 soil cores will be collected from each plot two times per season: the first within 1 week of planting and the second shortly following harvest. SCN eggs will be extracted from each soil sample collected from each plot and the number of SCN eggs in the sample will be counted. Initial and final season egg counts will be used to calculate SCN reproductive factor, the ratio of the number of eggs collected at the end of the season as compared to the number of eggs collected at the beginning of the season. Effectively, SCN reproductive factor measures how well a particular management strategy is controlling the ability of SCN to reproduce.
Additionally, each plot will be scouted and rated on two occasions for the severity of SDS foliar symptoms beginning in mid to late August. In addition to visual scouting, aerial imagery will be collected at the two scouting times to aid in the evaluation of SDS foliar symptom severity.
Disease response will be measured in each plot for both SDS and SCN using three measurement tactics:
1. For SCN - SCN reproductive factor
2. For SDS - SDS foliar disease severity (visual rating and aerial imagery)
3. For both diseases - Yield response as compared to non-treated control plots
Data will be analyzed by all possible combinations of treatment and location for the three disease response variables described above.