Location: Vegetable Crops Research
Project Number: 5090-21220-006-040-S
Project Type: Non-Assistance Cooperative Agreement
Start Date: Aug 1, 2023
End Date: Jul 31, 2026
Objective:
The purpose of our ongoing research in 2024 was designed to determine if mixtures of biorational pesticides and nutritional supplements labeled for use on potato resulted in reduced efficacy (antagonism) against Alternaria solani (see Appendix A). In 2025, we wish to explore these combinations in greater detail where we plan to examine different cultivars of potato combined with different delivery volumes. The 2024 investigations were conducted using ground-applications delivered at 35 gpa. In 2023, the insecticide comparisons were designed to mimic aerial applications and were delivered at 4.5 gpa. These are very disparate application conditions and in 2025 experiments we plan to i) evaluate select pesticide combinations under two delivery volumes. Cultivars of potato are known to respond differentially to combinations of pesticides (Barbas et al. 2024) and associated levels of phytotoxicity, and we also plan to ii) investigate how select pesticide combinations can result in phytotoxicity among commonly grown cultivars representing different market classes. Finally, we plan to iii) implement RNA sequencing on different cultivars subjected to pesticide combinations applied at very different delivery volumes.
Approach:
Objective I. Field based bioassays measuring antagonism. In 2025, we plan to investigate the control of the Colorado potato beetle and early blight under a 3 X 2 X 2 factorial analysis with 6 replicates per experimental condition. Field based experiments will be arranged with 3 main-effect levels of potato cultivar (cvs. Yukon Gold, Snowden and Russet Burbank), 2 main effect levels of delivery volume (5 vs 35 gpa), and finally 2 levels of pesticide main effects (simple vs complex) will be evaluated. Simple pesticide combinations will be defined as two-way combinations of a single-site mode-of-action (MoA) insecticide together with a single, multi-site MoA fungicide. Complex pesticide combinations will be defined as three-way combinations to include two fungicides (single-site and a multi-site MoA), two insecticides (single-site MoA plus an associated penetrating adjuvant) and finally a relevant combination of foliar nutrients used in our 2023-24 experiments. Insecticide treatments could include spinetoram (Delegate), abamectin (Agri-Mek), chlorantraniliprole (Vantacor) or the new dsRNA ledprona (Calantha). Candidate fungicides can include chlorothalonil (Bravo), mancozeb (Dithane Rainshield), boscalid (Endura), and difinoconazole (Initiate), applied as simple mixtures or as complexes with mixtures of insecticides and foliar nutrients. Foliar-applied nutritional components will again include: BioGrow 3-12-0, BioForge, NUE Mag, Max Set 28 and SetMore Base.