Management of Rotylenchulus reniformis and Meloidogyne incognita on Gossypium hirsutum in Alabama and the economic impact of additional fertilizer and nematicide applications

Abstract

The reniform nematode, Rotylenchulus reniformis and the southern root-knot nematode Meloidogyne incognita are some of the most damaging plant parasitic nematodes on upland cotton in the United States. Management strategies often reduce nematode populations without increasing yield. The overall objective of this research was to integrate additional fertilizer and nematicide combinations into current practices to establish economical and sustainable nematode management strategies. Microplot and field trials were run to evaluate fertilizer and nematicide combinations applied at the pinhead square (PHS) and first bloom (FB) plant growth stages to reduce nematode population density and promote plant growth and yield. Cost efficiency was evaluated based on profit from lint yields and chemical input costs. Microplot and field trials were conducted throughout two growing seasons (2019 – 2020). Data combined from 2019 and 2020 suggested a nematicide ST + (NH4)2SO4 + Vydate® C-LV + Max-In® Sulfur was the most effective in increasing seed cotton yields in the R. reniformis microplot trials. In R. reniformis field trials, a nematicide ST + (NH4)2SO4 + Vydate® C-LV at PHS supported the largest lint yield and profit per hectare at $1175.87. This combination increased profit by $137 per hectare when compared to treatments with no nematicides. In M. incognita microplot trials, an application of 28-0-0-5 at PHS resulted in the lowest M. incognita eggs per gram of root and the combination of a nematicide ST + 28-0-0-5 + Vydate® C-LV + Max-In® Sulfur at PHS and FB resulted in the highest seed cotton yields. In M. incognita field trials, a nematicide ST + 28-0-0-5 + Vydate® C-LV + Max-In® Sulfur at PHS and FB supported the largest lint yields and profit per hectare at $784.00, resulting in a $54 per hectare increase over treatments with no nematicides. These results suggest that combinations utilizing fertilizers and nematicides in addition to current fertility management show potential to promote yield and profit in R. reniformis and M. incognita infested cotton fields.