Date of Graduation

12-2018

Document Type

Thesis

Degree Name

Master of Science in Plant Pathology (MS)

Degree Level

Graduate

Department

Plant Pathology

Advisor/Mentor

Terry Spurlock

Committee Member

John Rupe

Second Committee Member

Terry Kirkpatrick

Third Committee Member

Terry Griffin

Keywords

Nematode Fumigation, Nematode In Soybeans, Root-knot Nematode, Site-specific Management, Spatial Analysis, Yield Prediction

Abstract

Aerial imagery offers great potential as a predictive scouting method and could allow growers to better understand crop performance over time. Evidence suggests that the seed treatments fluopyram and abamectin result in decreased reproduction and root galling by Meloidogyne incognita, but yield protection in fields with higher or different nematode pressure is unclear. The objective of this work was to determine the efficacy of these seed treatments compared to 1,3-dichloropropene (1,3-D) applied site-specifically and then predict where these might best be applied to other fields. In a soybean field infested with M. incognita, apparent electrical conductivity was highly correlated with sand content, and treatments were applied the total length of the field, across two soil textural zones. Fluopyram and abamectin seed treatments were compared to seeds without a nematicide seed treatment (control) and seeds without a nematicide seed treatment but planted within 1,3-D treated areas. Historical satellite images, normalized difference vegetation index (NDVI) and near infrared (NIR), from Sentinel-2 at 10-meter resolutions were compared to yield to determine if correlations with crop performance were evident over time. In 2016, treatment yields were not significant by zone, but yield was greater in the 1,3-D strips than all other treatments, while fluopyram and abamectin were not different than strips lacking nematicide (P=0.001). In 2017, 1,3-D strips had higher yield than all other treatments in both zones except for residual 1,3-D treatments that were applied in 2016 in Zone 2 (P=0.01). Fluopyram, abamectin, and the control treatments were not significantly different in Zone 1. Treatment effects for all treatments differed between the two textural zones (P=0.01). The distribution of M. incognita at harvest was uniformly distributed by treatments (P=0.08), suggesting that 1,3-D could be used as a two-year control and would be economically beneficial as a whole-field application when a susceptible soybean is planted. In 2017, NDVI and NIR observations were clustered, meaning that data are significantly positive for local spatial autocorrelation (P<0.05). Seven surrounding fields were further observed and 100% of analyses were clustered using NDVI and NIR images from multiple snapshots throughout the 2017 growing season. Initial analyses indicated correlations with yield, suggesting opportunities for prediction and that site-specific application of 1,3-D in these fields might be beneficial when susceptible soybean varieties are planted.

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