Using Remote Sensing to Determine the Response of Resistant and Susceptible Wheat Varieties to Fungicide Application.

A field trial was conducted at the Garden City Research Station in southwest Kansas to determine whether normalized difference vegetative index (NDVI) can be used as a tool to improve the decision making process of fungicide application. The effect of six foliar fungicide products (Aproach ®, Aproach prima ®, Tebustar ® , Prosaro ® , Absolute maxx ® , and Twinline ® )  on yield and  NDVI value  before and after application were evaluated in a randomized complete plot experiment replicated three times on  a below-average (TAM 111) and in an above-average (Oakley CL) disease resistance wheat variety Foliar fungicide treatments were applied after the flag leaf was fully emerged and the ligule was visible (Feekes GS9), and NDVI was measured prior to and 30 days following fungicide application to assess the effect of the fungicides on plant health. Grain yield was measured at harvest maturity. Stripe rust was the most prevalent leaf disease in the study.  Change in the NDVI was not a function of foliar fungicide for the variety Oakley CL, but was for TAM 111. The degree of change in NDVI 30 days after application to TAM 111 offers input on the effectiveness of the fungicide on the disease control. NDVI in the no-fungicide control treatment decreased by 0.07 for TAM 111, compared to 0.01 for the same variety treated with foliar fungicides TebuStar ® and Twinline ®, 0.02 for Absolute Maxx ®, Prosaro ®,  and combine application of Aproach ® and Aproach prima ® and 0.03  for Aproach prima ®.  Likewise, grain yield was not affected by fungicide application for Oakley CL, but was for TAM 111. In general, the higher the change in the NDVI the lower the yields. However, it is difficult to make much of this relationship with such limited data. Additional data and research is needed to further test this relationship.