ABSTRACT
A Verticillium wilt nursery was rated twice for incidence of wilt in 1040 plots. Aerial, color, infrared photographs of the nursery were used to determine the reflectance of near-infrared, red, and green color bands, and various combinations of these bands. Twenty-five cotton lines were replicated in > 8 plots, including the susceptible variety ‘Lankart 57' and the Verticillium-tolerant variety ‘Paymaster (PM) 147'. Incidence of wilt from the entire nursery was most highly correlated with reflectance of the green band. Incidence of wilt averaged 6 plants/plot for Lankart 57 and 2 plants/plot for PM 147 on 19 July, and 12 and 6 plants/plot on 18 August. However, reflectance of the green band averaged 146 for Lankart 57 and 150 for Paymaster 147 (not significantly different). Within a cotton line, reflectance of various color bands or band combinations was associated with incidence of wilt, but only for 8 of 25 cotton lines with the July rating, and 4 of 25 cotton lines with the August rating. Remote sensing with aerial color infrared photography can not replace visual rating for cotton lines in a Verticillium wilt nursery.
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