Texas Plains Cotton: Pests Mostly Quiet, False Chinch Bugs on the Rise

False chinch bugs. Photo: University of Tennessee

Despite some cooler days, we have had enough hot weather and time without rainfall to give us some clues as to our early damaged and cold shocked crops and whether they have seriously damaged and limited root systems, or if they will work well enough to develop crops properly.

There are some stressed dryland fields, but given the situation, I am starting to have confidence that our crops roots have at least some worthy capacity to keep pace with fruiting and developmental needs. The majority of our cotton is blooming and setting fruit well, but just barely, with larger bolls being very hard to find and grain crops developing well.

There remain many issues available out there to sneak up on any field, but on the whole, few fields have so far hosted any economic pest issues, weed control looks like a solid performance with a few missteps under unrelenting pressure, and agronomic issues are running at least as well as hand-to-mouth in the worst situations.

Finding and identifying those few pest issues, weed missteps, and pressing agronomic needs among the many fields out there with no major issues is challenging, but missing the few issues would prove very costly. Here’s to taking a deep breath and staying sharp with most crops’ ’crunch time’ right around the corner.

Cotton

This week our Plains Pest Management scouting program cotton ranged in stage from ½ grown square to 7.2 NAWF (node above white flower) with most fields coming in at ¾ grown square to 1st bloom. I estimate that about 60-70% of our cotton fields are blooming at this time.

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While there are few large bolls in field yet, boll set and fruit retention has remained very good over the past few weeks, correcting for a rough fruit set start in June. Our fruit drop ranged between 2.7% and 29.2% with most fields falling between 3% and 12%.

There are a few exceptions this week in our program fields with fleahoppers being the only cause for higher drop in particular fields. Fleahopper populations do tend to increase through early summer and peak near the second week of bloom, at which point they are no longer an economic concern. Fleahoppers will then seek to feed either on pollen (and not cause any damage to the blooms or bolls) or on bollworm eggs and worms (where they actually become a beneficial).

As this fleahopper population trend continues in some fields this week, some are just not blooming yet, giving the fleahopper nothing else to feed on except squares, causing the higher fruit loss, often resulting in those fields coming in over 20% drop. These fields did require treatment this week. Fields that were in similar situations last week, the fruit loss reversed and retention increased post treatment quickly.

We are still not seeing Lygus or bollworms in our program cotton at any level yet, but the potential for issues remain. We are picking up 2-3 bollworms per ear in corn at this time with most caterpillars being in the 2nd instar, but did not see any clue in our program cotton.

We began gathering data from a sentinel plot designed to monitor the efficacy of differing Bt technologies this week. In that trial, we are gathering a ridiculous amount of data from plant inspections, in the neighborhood of 250 whole plant inspection at once, plus about 1,500 fruit damage inspections.

For a reference as to pressure from bollworms this week, we found only 243 eggs per acre and an even less noticeable worm population in the non-Bt plots. With known resistance afoot and a proven resistance level this year in other growing areas to the south, we really should be scouting all Bt technologies for bollworms and following our old standby thresholds of 8,000-10,000 bollworms per acre or 6% harvestable fruit damage.

For other Lepidopteran cotton pests, such as beet armyworm or cabbage looper, all Bt types are giving very good control at this time. We are picking up some noticeable pressure in our non-Bt fields, but little more than a hint of damage in our Bt fields.

For the past few weeks, we have had several reports about populations off to our east with false chinch bug infestations that often reached economic levels. In our farthest eastern fields, we are picking up this pest at an increasing but still sub-economic level. Please consult our cotton insect guide for control and ET suggestions.

A good rule of thumb for pre-bloom cotton is 25 false chinch bugs per plant. These pests could cause square loss from direct feeding or general plant feeding in very heavy numbers.

Corn

Our program corn ranged in stage from V5 to early dough stage with most older fields being around blister stage. Pollination looks to have gone pretty well through the key developmental stages with timely irrigation for our fields but not perfect with a few periodic tips and kernels blank.

This is far below the potential loss during the high heat the fields experienced but is a testament to timely agronomic inputs from our growers understanding key needs at key times during stress situations.

Surprisingly, our banks grass mite population is not blooming in the post-tassel, heated situation. For most fields our mite damage ratings were well below 1 on the Texas A&M AgriLife 0-10 mite damage rating scale with 3.5-4 being ET.

Only one field ranged notably higher with an across the field average rating of 1.63. This field had a few small pockets of mites at ratings of 3 and 4. We are noting a healthy population of mite destroyer beetles and their larva around most mite colonies helping keep them in check.

No fall armyworms or western bean cutworms were found in our post-tassel fields this week but some feeding was noted in whorl stage corn. Disease issues seem to be holding steady at light with multiple pathogens infield at low levels.

The bollworms (also corn earworm if you prefer) we are finding in our corn should be of limited or no economic significance as they compete for dominance limiting the damage to only the ear tip.

Sorghum

Our program sorghum ranged in stage from V4 to early bloom. We again found limited pest issues in our sorghum. We did discover sugarcane aphids (SCA) in our research plots at Halfway this week at an early infestation level of about 10% infested V10 stage plants and an average of 0.25 aphids per leaf.

We will be watching all of our fields for SCA very closely. We found no sorghum midge or headworms on our few blooming heads but did note more light whorl stage feeding from both CEW and FAW. A very few yellow sugarcane aphid damaged leaves were found this week on older whorl sorghum and one pocket of BGM were found in a field otherwise short of insect activity.

Greenbugs have been absent from any of our checks this year so far. Our latest sorghum is hurriedly getting sorghum herbicides applied to keep those issues at bay. We should still be checking all blooming fields for sorghum midge daily.


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