Texas Blacklands Cotton: Insects Quiet but Keep Scouting

GENERAL

Cotton across the area have developed nicely over the last two weeks with all the fields I am checking in the bloom stage. The recent rains over the July 4th weekend this past weekend have been very beneficial to the crop except for it has held some producers out of the field from being able to spray weeds and plant growth regulators.

Insect activity in cotton is still high, but currently there are not any major widespread issues in the cotton crop. Grasshoppers remain active in the environment and have been found in some area cotton fields. Grasshopper number have not yet reached a level or caused enough damage in these fields to justify treatment.

Bollworm moths remain active in the area, but larvae numbers and damage are not severe enough yet to justify treatment on cotton. Thanks to the timely rains our crop has a good fruit load, and Potassium (K) deficiencies symptoms are starting to be found in area fields.

Corn and sorghum acres continue to progress closer and closer to harvest, with sugarcane aphid number increasing in area around Waco and further south which could cause an issue at harvest if they are left untreated.

COTTON

The area cotton crop looks good right now thanks to the timely rains. Honestly, earlier this year I would not have suspected our crop to turn around and look as good as it does, because of the cool temperatures and excessive moisture received during the month of May. There are not any major insect issues in area cotton right now, but there are a few pests we need to continue scouting for including bollworms and grasshoppers.

Potassium deficiency symptoms are also still being found in area fields, but thanks to the rains last weekend it does not appear to be getting worse. Bollworm moths are still being found flying around area fields and eggs are easy to find, but the current egg lay is still light.

AgFax Weed Solutions


As of now our Bt trait packages are holding up against the current bollworm pressure, and I am not finding any significant damage is our two-gene (Bollgard 2 and TwinLink) technology or our 3 gene technologies. I have a bollworm sentinel plot that includes all available Bt trait packages and a non-Bt variety outside of Abbott and have only found about 8% damage in the non-Bt variety and no damage in any of the Bt varieties.

As we continue to progress in the season, we need to keep an eye out for bollworms and their damage and treat when the economic threshold is reached. The new threshold for bollworms in cotton is 6% damage fruit (squares and bolls) with live worms present.

Insecticide options for bollworm management include Prevathon at 14-21 FL oz/acre and Besiege at 7-12 fl oz/acre. Bollworms will remain an issue for area cotton fields, until they accumulate about 350 growing degree days (heat units) past cutout (5 nodes above white flower).

Grasshoppers are still active in the area, and I have started to pick up some moving into area the edges of area cotton fields. As of now I have not seen enough grasshoppers or their damage in any cotton field that would justify treatment, however as our grain crops continue to be harvested and our pastures and road ditches get cut and/or start drying down they will be moving to cotton to feed.

Fields should be treated for grasshoppers when there is significant defoliation (30% or more) and treating field edges can usually prevent damage from moving further into the field. There is various insecticide labeled for grasshopper management in cotton, but the best product we could use is Prevathon (now called Vantacor) at 10 FL oz/acre (Vantacor rate = 0.90 FL oz/acre).

By using Prevathon we preserve our beneficial insect that are in the field helping keep aphids, spider mites and bollworm numbers below the economic threshold.

SORGHUM

Sugarcane aphid populations have remained low for most of the state of Texas, until about seven days ago. Recently I have received reports of sugarcane aphid number increasing in the Southern portions of the state, and earlier this week I was called to a field between Riesel and Marlin, where sugarcane aphid numbers are increasing to levels close to the economic threshold.

Even though most of the sorghum in the area is past seeing economic yield loss from sugarcane aphids, we do need to keep watching their numbers so we can avoid harvest issues that arise from the honeydew they produce. When managing aphids this late in the season we are less worried about length of residual the insecticide will provide and more worried about our pre harvest interval.

Products that can be used include Transform at 1.5 oz/acre which carries a 14-day PHI, Sivanto at 4 fl oz./acre and carries a 14-day PHI, and Sefina at 6 fl oz/acre which also carries a 14-day PHI.




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