Blue Disease, Nematodes Aren’t the Only Threat in 2019
Bob Kemerait | 3/20/2019 | Southeast FarmPress
Too many cotton stalks are left in the fields. Incessant rains that began last fall kept farmers from harvest and from destroying what remains.
I told growers that December freezes had killed the remnant plants, thus depriving nematodes a food source and a newly-discovered virus a reservoir for aphid vectors. But days of unseasonably warm weather have proved me wrong and, like Lazarus, stalks are coming to life as new buds appear. At best, these ghosts from last year will be of no consequence for the 2019 cotton crop. At worst, they will feed awakening nematodes and hungry aphids that acquire a potent virus and spread it to a new crop.
Speaking at an Extension meeting in southwestern Georgia, I encouraged cotton farmers to recognize the symptoms of plant-parasitic nematodes, and the Cotton leafroll dwarf virus(CLRDV) in their 2019 crop. Recently confirmed in Alabama, Georgia, Mississippi and South Carolina, this virus is known in Brazil and elsewhere in the world as the causal agent of “Blue Disease,” which is known to cause significant yield losses.
To best protect your yields, it is critically important to take precautionary steps to reduce risks. Identifying symptoms of nematodes will help growers plan for management; however when they appear it is impossible to further protect the crop. Collecting soil samples after harvest and having them analyzed for nematodes is an important preemptive practice. Results allow growers to take necessary management steps for the upcoming season before damage occurs.
Symptoms caused by CLRDV may include crinkled, puckered leaves, reddening of the entire plant, distortion of blooms and abortion of squares and bolls, and a “crazy-top” where shortened internodes and absence of fruit give the cotton plant a “whip-like” appearance. Although there is much to be learned about this virus, there is no doubt that it can take a severe toll on yields in some situations.
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