Oklahoma Crops: Section 18 for Transform Use in Cotton and Sorghum.

White Sugarcane Aphid

Much needed rain has falling over most of the state with the exception of some areas. The forecast is calling for rain and cooler temperature starting from Sunday June 17 and continuing through Thursday June 21. Hopefully these events will occur. Soil temperature have reached temperature that has not only retarded root development but as also caused mortality in some fields. The forecast will help with these conditions.  

Cotton

Extreme heat with dry and windy conditions have caused 2018 cotton season to be a challenge in most of the state. Off target herbicide contamination has also added to the many difficulties on this year’s crop. Hopefully with the weather “breaking” growing condition will improve and the crop will get back on track. The old adage that cotton is a heat “loving’ plant is false. Cotton is a heat tolerant plant. Nothing including myself does well in this heat and conditions.

I cannot stress enough after emergence scouting of the field must start and continue on a weekly basis until termination of the crop. Thrips infestation have been light to nonexistent state wide with few exceptions in Tillman county and other areas. False chinch bugs have not developed which is good news. Conditions like this year usually brings problems from this pest. Where adequate moisture is available and weather condition that have not been extreme the crop development is doing excellent.

Transform – Emergency Use Permits

The EPA has granted Oklahoma a Section 18 Emergency Use Permit (EUP) for Transform WG to control plant bugs in cotton, and in sorghum, to control sugarcane aphid during the 2018
growing season. In cotton, Transform can be applied at 1.5-2.25 fl. oz. per acre to control “plant bugs”, which includes several Lygus species (pale legume bug, tarnished plant bug, and western tarnished plant bug) as well as the rapid plant bug.

EPA granted this EUP in part due to the expected ncrease in planted acres of cotton in Oklahoma, especially in areas where alfalfa is also grown.

This Emergency Use Permit expires October 30, 2018. Plant bugs cause deformed bolls, square and boll shedding, stunted plant growth and small black spots on the bolls. Oklahoma does not have a treatment threshold set for plant bugs. Texas A&M suggests sampling with a sweep net or drop cloth. Sweep net is best before bloom, and drop cloth works better after peak bloom.

In sorghum, Transform to be applied at 0.75-1.5 fl. oz. per acre to control sugarcane aphid. Current thresholds for sugarcane aphid are It has a restricted entry interval (REI) of 24 hours. It should not be applied within 14 days of grain harvest, or 7 days if grazed or harvested for grain. This Emergency Use Permit expires November 30, 2018.

We encourage growers to inspect their sorghum fields once a week. When aphids are detected, increase sampling to two times per week. Look at three consecutive plants and examine one upper and one lower leaf on each plant. Estimate the average number of aphids found per plant. Then move 5 feet and sample three more consecutive plants.

This is considered one “stop”. Next, move 50 feet from the first spot using an inverted “U” shaped pattern in the field and sample six more plants for the next stop. Collect counts for nine stops (for 54 plants) and estimate the percentage of plants that averaged at least 50-125 aphids per plant.  

The current recommendation for control of sugarcane aphid is to treat if 20% of plants are infested with 50-125 aphids per leaf before panicle emergence, and if 30% of plants are infested with 50-125 aphids per leaf after panicle emergence. Do not spray until suggested thresholds are reached, but if needed; apply the spray with the highest amount of water carrier as possible (5 or more gallons/acre by air, or 10 or more gallons/acre by ground).

Spraying too early and with inadequate coverage may require a second application from aphid recolonization. In order to minimize pollinator protection, this product should be applied before 7:00 am or after 7:00 pm, or in the unlikely situation that temperatures drop below 55 degrees F at the site of the application (an extremely rare event until later in the fall).

In addition, for cotton, the applicator should attempt to notify any beekeepers with hives within 1 mile of the treatment area at least 48 hours before the product is applied. In sorghum, Transform should not be applied during flowering (less than 3 days pre-bloom until after seed set).

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