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Field and Forage Crops |
The weather is not favorable to most cotton producers, with dry conditions continuing over most of the state. Let's hope for significant changes soon. This coming week is probably the last opportunity for growers to plant a cotton crop with reasonable yield expectations.
Thrips levels have increased this past week. Adults migrating into cotton will likely continue to increase during remainder of May and into the first week of June, especially where dry conditions persist. So thrips probably will not be giving growers much of a break for a while.
When either a seed treatment or a granular in-furrow insecticide plays out, thrips levels and damage to cotton can increase pretty dramatically. Be sure to at least spot check a sample of cotton fields for thrips and their symptoms twice a week. Focus initially on those cotton fields with a higher probability of damage, such as fields planted in April, fields with seed treatments more than 3 weeks after planting, or particularly dry fields in which insecticide uptake may be compromised. If recent damage is present and thrips are found, expand your inspections to other additional fields.
Although several adult thrips per plant can certainly damage cotton, the presence of the very small, yellow, wingless, immature thrips means that reproduction has occurred and a higher potential for damage exists. A hand lens is recommended for viewing the immature thrips. If moisture levels are adequate, five true leaves or nodes typically signals the end of thrips damage to cotton.
Outside of the possibility of cutworm damage on scattered reduced tillage cotton fields, the initiation of June squaring typically signals the onset of potential pre-bloom budworm and/or plant bug problems.
This year has the potential to present peanut growers a challenge in managing thrips. Populations of thrips are high and in some areas soil moisture is marginal which is limiting the effectiveness of some in-furrow, at-plant insecticide treatments. Adequate rainfall will go a long ways toward correcting the concern over insecticide performance in most areas. The use of a follow-up foliar insecticide treatment is advised only if the percentage of newly-opened leaflets with serious thrips feeding damage exceeds 25 percent (or at least 1 out of every 4 leaflets has damage). Despite concern over higher levels of virus compared to last year, the use of multiple foliar sprays for thrips control is NOT recommended because research trials have not demonstrated it to be of any benefit. This year is also shaping up to be a year for spider mite problems and foliar insecticide sprays have the potential to increase the likelihood of problems with spider mites.
Employment and program opportunities are offered to all people regardless of race, color, national origin, sex, age or disability. North Carolina State University, North Carolina A&T State University, U.S. Department of Agriculture, and local governments cooperating.
Last modified on May 24, 2004 by Stephen J. Toth, Jr.