Texas: Sugarcane Aphids, Spider Mites in Sorghum, Corn; Cotton Finishes ‘Crunch Time’

Sugarcane Aphid

Cotton

This week our scouting program cotton ranged in stage from 5 nodes above white flower (NAWF) to absolute cutout at 3.5 NAWF or less with most fields having recently reached cutout. Fruit retention still looks good as the average last effective bloom date of August 24 fast approaches. I am concerned about the small stature of the crop and the short effective bloom window we have had for most of these fields that have been in cutout for a week or more but the boll set percentage remains high.

Of the fields that reached cutout earliest, boll fill looks pretty good and appears to be sporting as many bolls as these ‘diminutive’ plants can possibly hold. Plants recently reaching cutout will need as much water as possible to hold as much fruit as they can hold for a while longer.

We had one cotton field near Tulia with economic Lygus problems again this week. In this instance, a neighbor swathed and bailed adjacent CRP, apparently chasing the healthy Lygus population into the irrigated cotton. We are picking up ultra-light mites and cotton aphid in a few data set here and there.

Corn

Our corn stages remain grouped into the three growth stages. Our oldest corn fields are all in dent with a few starting to show a 10-15% starch line. Our mid-group is in dough to late dough stage while our late corn is between tassel and blister stage. Each of these three groups has a differing set of issues now and over the upcoming weeks. All stages continue to look good in general with good yield potential.

The mites, banks grass mites (BGM), on our oldest program corn looks to be crashing after a long hard control battle. In addition to the six spotted thrips for predator help, we are finally seeing predatory mites join the mix while the mite destroying lady beetles remain mysteriously absent for the most part. The crashing of mites through treatment and predation has finally put these older fields ‘on the short rows now.’ We should have one or two more weeks of spot checking just to make sure, but once these fields reach 15-25% starch line, they should only need to dry down for harvest.

In our mid-maturity corn grouping the mites are another issue. We have already needed to recently treat 95% of our pro-gram fields in our southern scouting area from Plainview south and we are experiencing a rapid increase this week in mite pressure for this stage of corn in our northern area throughout Swisher with about 45% already requiring treatment.

Many of these northern program area producers have never grown corn before and have never faced the BGM challenges. We remain hopeful that cooler temperatures over the past few days will help hold the BGM from progressing farther.

The BGM remains low on our latest corn maturity group, but if the mite trend continues, we should be scouting thoroughly for mites in these fields over the next few weeks as these fields move into dough stage. As fall nears, the amount of daylight per day decreases, temperatures decline, and the amount of ‘dew’ increases, all factors that can hinder mite populations.

These later fields have the best chance of avoiding mite issues for these reasons, but for the same reasons these fields have the most risk of corn disease problems. This week our corn disease ratings did not significantly increase.

This week our FAW moth trap catches increased for Hale Southern County and in Lubbock County. We should remain vigilant, if not preventative for FAW in any later non-Bt or lesser Bt traited corn this week. Older fields might not be as attractive to the FAW, but that is no guarantee.

Sorghum

Our program sorghum ranged in stage from 50% bloom to soft dough. In addition to SCA issues, we are steadily finding BGM in fields. While none of our program sorghum fields have reached an action threshold for mites, I have independent consultant reports that show some area fields have. None of the insecticides required to treat SCA have any impact on BGM, but they are also beneficial soft that has allowed the predatory mites and six spotted thrips to feed on the mites unimpeded.

If needed, there are two labeled and proven products for mite control in sorghum that are also beneficial soft Onager and Comite II. Use of these products should not interfere with aphid control. Please consult labels for any treatment mixing needs.

This week we also started finding a few headworms, all of which are CEW, in sorghum heads. We will be watching closely for any economic concerns as the bollworm population looks to be making their ‘end of summer spike’ at this time. We would expect many of these eggs to be lain in the latest corn fields, but sorghum or cotton is not immune and could prove very attractive to high numbers of egg laying moths.


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