A website from UGA Cooperative Extension

Row Crop Disease Update – Kemeriat

  1. Travelling across the state, I am seeing a significant amount of “regrowth” on cotton after the lint has been picked.  In many cases the stalks have already been mowed; however there the plants are growing again.  There are several points for you to consider on cotton regrowth.
    • As long as the cotton plants are alive, which will be until they are killed by frost or until the grower destroys them, they will be a wonderful food source for plant-parasitic nematodes (root-knot, reniform, sting, Columbia lance).  Although there can be no more damage to the crop once the cotton is picked, the living cotton plants will continue to build nematode populations that must be battled next time.
    • We may see ample symptoms of the Cotton Leaf Roll Dwarf Virus (CLRDV) on cotton regrowth.  Last season it was VERY common to see the symptomatic “crinkled” leaves on the regrowth.  Again, this can’t hurt this year’s crop, but will both confirm for you that the virus was present and it MAY serve as an inoculum source for aphids to vector the virus from the cotton to winter weeds, e.g. white clover and henbit, which could serve as a reservoir for infecting cotton next season.  We know that CLRDV survives in the cotton and the winter weeds.  We do  not fully understand the implications for next year’s cotton crop, but the common sense tells me there could be a problem.
    • Taking nematode samples is a very important thing to do at harvest on all crops to determine both the kind of nematodes in field (important for rotation decisions and variety selection) and size of the population.  IF THE SOIL IS POWDER DRY OR ROCK-HARD, there is little sense in collecting the samples as they will not be representative of the real problem.  Now that we have rain and soil moisture, it is a PERFECT time to collect samples, and will be until the soils cool or become dry again.
    • Destroying cotton stalks deprives the nematodes of a feeding source, but costs time and mone to do.  Unfortunately, I do not have data to base a true economic analysis on or data to show how much the nematode populations are reduced.  However, there is no doubt that the earlier the stalks are destroyed, especially when we have delayed frost and warmer winters, pulling stalks can only help in our battle against nematodes and my help in management of CLRDV.
  2. Cotton Leaf Roll Dwarf Virus has caused very little loss to our cotton crop in Georgia in 2019 and I know of only two small fields where I would say loss was significant enough to document.  However, those of us on the UGA Cotton Team agree that the symptomatic plants, though few in number, were likely present in most of our fields this past season.  We still do not know what, if any, impact this newly-recognized disease will have on cotton production in the USA, but be assured we are conducting the research need to both understand the virus and to manage the disease.  For 2020, there is little that we are adding to our current management recommendations- destruction of winter weeds ahead of planting, and, possibly, avoiding late-planted cotton where possible.
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