Abstract

Nematodes have become more problematic in North Carolina cotton production over the past few years, primarily due to the loss of aldicarb as the predominant means of control. Growers have adopted in-furrow liquids as their primary control measures for thrips, and many growers are no longer equipped to apply granular insecticides. Cultivar tolerance to nematodes are primarily specific to root-knot nematodes, however, several other species also affect cotton. Velum Total™ has been evaluated as a control measure but can only be used by growers who are equipped to apply in-furrow liquids.  Nemastrike™ seed treatment (released 2018) is touted to provide broad spectrum control of nematodes. The research objectives were to evaluate effect of Nemastrike™ on plant growth, symptomology, and numbers of  nematode species, and to evaluate the effect of Nemastrike™ on yield of cotton in multiple environments with a history of problematic nematode pressure.

Replicated trials were conducted in two separate fields during 2018. Fields were chosen based on soil type (deep sands), and history of nematode pressure. Treatments consisted of both Nemastrike™-treated and non-treated seed of DP 1646 B2XF from the same seed lot.  Non-treated seed received base seed treatment of both fungicide and imidacloprid to control seedling diseases and thrips.  Liquid imidacloprid was applied in-furrow in both treatments to negate any effect of thrips. Composite soil samples were collected in each plot prior to harvest.

In conclusion, yields were improved by Nemastrike™ seed treatment in one of the two treated fields. Yield responses appear to be environmentally dependent and not necessarily predicted by soil test results.  In one environment, end-season nematode numbers were higher in treated plots, possibly due to greater root mass, although yields were similar between treatments in this environment.  Nemastrike™ seed treatment may provide some suppression of nematodes and may improve yields in some cases.  The frequency of yield responses can only be determined through additional research in a larger number of environments.