Through Harvest, Be Vigilant For Late-Season Pests
February 26, 2009 Ever seen a high school football team rushing the water cooler during two-a-days, vying for a cold drink in the August heat? That’s what it could be like with late-season pests during 2007.
Populations have been higher in many areas of the Cotton Belt, and it could get worse as the season continues, especially in the Delta and Southeast where field corn put a stranglehold on cotton acreage.
Fewer acres, combined with weather and other factors, caused heavy pressure from thrips early in the season throughout the South, according to LSU Agcenter research scientist Dr. Roger Leonard.
“One important fact to recognize is that overall cotton acres are down, period. So the insect pest populations that have been distributed over a large area will now be concentrated in fewer acres. So we should anticipate more problems from those same pests that occur on an annual basis in the late season – such as plant bugs, stink bugs and caterpillar pests,” Leonard said.
If early insect pressure was higher than normal because of reduced acres, late-season insects could be worse as a considerable acreage of Mid-South cotton was doubled-cropped behind wheat. With a very wide range in planting dates and the majority of that crop planted late – late for Louisiana is June – cotton will be very susceptible to high insect pest pressure.
“Some of this acreage was planted during the first and second weeks of June, therefore it is going to be attractive to late-season insect pest pressure after most of the crop that was planted on a normal time frame has finished up. As the early-planted cotton is harvested, total acreage will slowly dwindle, and pests will migrate to the fewer acres of later-planted cotton. This scenario provides for an island effect, so the pests funnel into the few cotton fields that have not yet reached full maturity,” Leonard said.
“The circumstances are set up for very heavy pressure – if you add everything up that has currently been put into play for the 2007 season, history tells us to expect heavier than average late-season insect pressure.”
Stay Ahead and Diversify
“This is more of an awareness issue than anything else,” Leonard continued. Sometimes if you know what to expect and know what to look for, then it doesn’t strike you quite as hard when they show up. Most of these fields will have to be continually scouted, and I believe we need to lower our expectation levels of product performance. With intense and persistent pest populations, we probably are not going to zero out pest populations with single insecticide application in many of the late-planted fields.
“With the plant bug/stink bug complex, it is important to rotate among the available products that currently are available,” he added. “Banging away with one product in four or five successive applications week after week, is probably not going to be the most effective way to manage the bug complex. Rotating among the different products will give farmers a much higher probability of maintaining successful control in those fields. Obviously this is not a guaranteed strategy, but it is certainly better than using one product time and time again,” Leonard said.
“… Farmers need to recognize the limitations of the Bt traits … Growers who planted varieties with a single Bt gene (which is the vast majority) will probably need additional protection from corn earworm and even armyworms, compared to those varieties that express two insecticidal genes, such as Bollgard II and Widestrike,” Leonard said.
Caption for photo:
Dr. Roger Leonard,
Research Professor and Jack Hamilton Regents Chair of Cotton Production,
LSU Agcenter.
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