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Serving: Central

Insects, rain set back Louisiana crops

Harvest of soybeans, corn and grain sorghum were all set back by rain last week in east central Louisiana. “Too much rain — 7 to 8 inches fell last week in much of Tensas and Franklin parishes in east central Louisiana,” according to Roger Carter of Agricultural Management Services.

Other parts of the region received from 1.2 inches to 3 inches. Rainfall chances are 30 percent and higher for most days this week.

Crop conditions reported by Carter in the Aug. 17. AMS Ag Report:

CORN: Harvest is perhaps 60 percent complete. Remaining harvest will be slower due to downed corn and wet conditions. Still no aflatoxin reported in our area, but there was some just to our north.

GRAIN SORGHUM: Webworms and midge still the major problem for late grain sorghum. Webworms are attacking heads as soon as grain begins to form. We are treating heading grain sorghum on a five-day interval with Lannate plus a pyrethroid. Pre-headed grain sorghum is also being treated for borers with pyrethroid with limited success.

Some grain sorghum is sprouting in the heads due to cloudy wet conditions. Harvest is 40 percent complete.

SOYBEANS: No soybeans were harvested last week due to wet conditions. Over 25 percent of soybeans are ready for harvest. Nearly half of those have been “Gramoxoned”. They will start “popping” when sun again dries pods enough.

The dilemma that some farmers face is that they have both soybeans and grain sorghum ready for harvest and both need it now.

Treatments of loopers and stink bugs scheduled for last week were delayed due to weather. Some treatments were applied on late Thursday, Friday and early Saturday (Aug. 14-16).

Stink bugs are reinfesting fields to “treatable” levels within seven to 10 days. Some fields which are near drying soybean fields are under more intense pressure.

We have lowered our threshold after the first threshold level was treated. Our threshold is now 60 to 75 percent of the first threshold (16 to 32 stinkbugs per 100 sweeps, depending on species and maturity of soybeans). And after the second threshold is reached, we lower it to 40 to 50 percent of the first threshold.

Cumulative damage by sub-threshold levels of stink bugs can destroy a crop. This is seldom mentioned when thresholds are discussed.

Delays of five to seven days when soybean thresholds are reached can cost farmers in quality and yield. One field on which applications were missed jumped from 28 per 100 sweeps to over 250 per 100 sweeps in 10 days. Damage in that field may be so bad that the soybeans may not be accepted at the elevator.

Banded cucumber beetles still are “exploding” in some fields. Thankfully they do not cause the same extensive damage that bean leaf beetles cause at similar numbers. We have adequately controlled banded cucumber beetles with 1/20 gallon of Brigade/Discipline/Sniper per acre.

Loopers are still a presence in many fields. Some fields are receiving the second shot of Intrepid. We have increased our low-end rate of Intrepid to 5 ounces per acre. Larvin at 1/8 and 1/7 gallon per acre gave excellent control of moderate to heavy populations of larger loopers. We will be assessing Steward at 1/18 to 1/16 gallon per acre soon.

Cercospora is appearing in most soybeans now. It is very ugly in several fields of late Maturity Group 4 and of early Maturity Group 5 that were treated with 4 ounces of Quadris plus 1/10 gal of Topsin L per acre at late R3. All wheat beans are being treated with same dosage and, if the soybeans justify it, a second shot of either Quadris or Headline plus Topsin or a single strong dose of Topsin.

COTTON: Open bolls present in up to 90 percent of the area’s cotton acreage. Youngest at 17th true leaf.

Eighty percent of the crop will not be scouted this week for insects unless stink bugs are an issue.

Several thousand acres are awaiting defoliant applications as soon as weather cooperates.

Spider mites are not as much of an issue on some cotton due to rainfall, but numbers are still present even where 7 inches of rain occurred. Zeal or Abba was applied to some acreage.

Salt marsh caterpillars seem to have almost disappeared in many fields after the rain. And we are finding many diseased or parasitized salt marsh caterpillars in sweeps.

Plant bugs are still a problem in all cotton following wheat. Our “go to” or standard treatment for plant bugs is still 1/20 gallon of Brigade/Discipline/Sniper plus 1/2 pound of Orthene per acre. One application of 1/24 gallon of Brigade + 1/24 gallon of Bidrin gave less control than our new “standard”. Residual from our new standard appears to be seven days or longer, but it is hard to assess with the erratic populations we are now experiencing. Additionally we are not under as intense pressure from plant bugs as we have been in previous years. But the “standard” is still better than anything else we have observed this year. A premix of those two products at those rates, if possible, would be helpful.

Diamond was added to “the standard” application at 6 ounces per acre for fall armyworms on nearly a thousand acres in Franklin Parish.

Cotton yields will be from 400 to 1,400 pounds per acre. We have dropped our estimates 100 pounds due to wet weather hard-locking some bolls and due to boll deterioration in open cotton. Our average could still be near 900 pounds per acre.

Tim White, Walter Myers, Wil Miller, Matt Myers, Lydia Ellett, and Roger Carter of Agricultural Management Services, Inc., are located in east central Louisiana, serving Catahoula, Concordia, northern Avoyelles, southern Franklin, and southern Tensas parishes.

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