I made comments two weeks ago about yellow peanuts needing sunshine and that they would soon green back up. They did. Well, those comments were not to be confused with crops having actual nutrient deficiencies. I have seen several acres of peanuts and also cotton and grain sorghum with iron chlorosis and possibly other nutrient shortages. The problem now is that we are near or at the time when we need to cease fertilizer applications.
Grain sorghum fields that have headed out recently may have headworm issues. Scout now for headworms. Very few greenbugs or spider mites have been found. For a copy of the Sorghum Insect Pest Guide go to: http://agrilifebookstore.org/ and find the B-1220.
Peanuts are hosting sub-threshold numbers of larva pests feeding on foliage. Weed control has continued to be a challenge. Leaf spot and limb rot are the primary pathogens of concern. Growers should already have applied a preventive treatment.
Cotton continues to make good progress. In some cases this last week we closed in on 5 nodes above white flower (NAWF). I generally do not like to hit the 5 NAWF (physiological cut-out) mark until the first week of August. This gives us a better opportunity to take advantage of the whole season. Hitting 5 NAWF by the last week of July puts us blooming at the top of the plant in approximately 15 to 20 more days or around August 10 to 15. That’s not bad from a conservative use of time. But we may have left a full week of continued fruiting time on the table, which might have been two more fruiting positions. The situation is not necessarily bad, but could become worse if growers try to push the plant to add top growth, which will not have time to contribute to yield and could detract from yield and quality.
It takes 30 days for a new square to bloom, so an August 26 bloom does not have a chance to make.
Cotton aphid populations have taken a turn for the better in most fields. Many fields needed treated last week to alleviate stress and prevent fruit loss. However, when I recently checked fields aphids were not building, possibly dispersing some, and ladybug numbers were building rapidly. A few green lacewing adults and parasitic wasp activity were noted.
Do not neglect aphids. Some fields may need to be treated.
Various worms are now active in conventional cotton. Primarily, the cotton bollworm is the concern, but some areas have square borers and armyworms. Bollworms are running from zero to around 10,000 worms per acre.
Chris Locke and Bryson Vadder, independent crop consultants, report treatable bollworms near Levelland and square borers around Morton. Keep close watch on conventional cotton fields for worms anywhere.
Cotton fields should be scouted carefully every 3 to 5 days during periods of predicted moth egg-laying activity. In fields with fewer than five squares per row foot (approximately 67,000 per acre), bollworm populations often collapse and cease to be a problem.
Eggs and newly hatched worms are usually found in the plant terminals and indicate possible outbreaks. Natural mortality agents such as weather and predators frequently control these pests before any damage occurs. Once worms have grown to larger than half-inch long, natural and insecticidal control may be less effective. Insecticides applied to control half-inch-long worms are only moderately effective.
Frequently, examining the upper third of the plant (leaves, stems, squares, blooms and bolls) is all that is needed to make a sound management decision. However, when eggs are being laid all over the plants or when 60 percent or more of the bolls are mature, whole plant counts should be used. Mature, unopened bolls are firm, cannot be dented when pressed between the thumb and forefinger, and cannot be cut easily with a sharp knife.
After bolls are present
Divide the cotton field into four or more manageable sections depending upon field size. Make whole plant inspections of five randomly chosen sets of three adjacent cotton plants in each section. Count the number of eggs, worms and key predators encountered and estimate the number of eggs, worms or key predators per acre using the following formula:
Number of worms, eggs or key predators counted multiplied by (the plant population divided by the number of whole plants checked) = the number of worms, eggs, or key predators per acre.
The plant population can be calculated on 40-inch rows by: counting the number of plants in approximately 13 feet and 1- inch row feet. Do this in at least 4 locations and average. Multiply that average by 1000. This gives you plants per acre.
Treatment may be justified when counts average 5,000 or more small worms per acre. However, if two or more key predators are found for each small worm, control measures may not be needed or a microbial insecticide may be used.
The actual treatment level will vary according to the ability of the individual scout to locate small larvae, the age structure of the infestation, maturity of the crop and crop value.