Texas Plains Pests: Cotton Passed Cut-Out; Mites, Aphids in Corn, Sorghum

General Status

The summer scouting season starts to draw to a close without any notable bollworm migration, flights, or cotton infestation to speak of while Banks grass mites and sugarcane aphids are keeping the pressure up in our late grain crops. The above average temperatures and apparent ‘rain free zones’ continue to task our irrigation systems past their capacity for another week while dryland crops not already made look to crumble to dust.

At least the bulk of our irrigated cotton fields can go into a maintenance irrigation mode and our older grain fields are in dry-down. Harvest is growing more intense for our older grain fields as more and more reach maturity and head to the elevators.

The feedback I have from these early harvests is on the disappointing side with drought and desiccation being the primary cause.

Cotton

All of our program cotton fields are past the absolute cut-out stage of 3.5 NAWF (nodes above white flower) with a minority of fields sporting less than 5% open boll. Our Floyd bollworm moth captured higher numbers of moths this week. Up to 211 for the week.

This is a major increase and high for the season but still represents a relatively low population available to reek their damaging havoc on cotton. In heavy bollworm seasons, these numbers can easily climb to over 400 per week.

With our Hale and Swisher traps  back down into the single digits this week and cotton progressing to its current stage, most cotton has very little to worry from bollworms at this time. Whether this increase in moth traffic for Floyd is the beginnings of a migration or a swarm of local moths freshly emerging from older corn, we do not know.

We do know that via the stage of most cotton fields the worms are too late to be an economic problem for these fields. Fields with large bolls at the top of the plant and missing any younger fruit would be very hard for bollworms to establish in. Lusher fields that may still be showing some younger fruit that the bollworm might be able to establish on have little to no chance of developing that younger fruit into a harvestable boll.

So concludes the first year in memory that I have not recommended a single cotton field for bollworm treatment. This represents at least one major issue our summer crops have missed this summer.

80% of our program fields were already past economic dam-age from bollworms as this week started. I only intensely scouted those 20% of the fields that were lusher that had a chance of boll-worms or other primary pest issues. We found no bollworms or eggs in any of our fields with the ‘last sweep.’

In these fields, I continued to find Lygus at notable but sub-economic populations of 1 Lygus per 3’ to 12.5’ row feet with the higher populations in the lushest of fields.

The only field where Lygus were not found was in a drip field with high yield potential that we had recommended treatment for Lygus last week. Fields such as this one might still be at risk for Lygus, for one more week but careful analysis should be given as to the fruit these Lygus would be feeding upon.

In many cases, the youngest of the fruit in-field will either be too young to make a harvestable boll this late or could be dropping naturally. However, if an economic population of Lygus of 1 per 2’ row feet or more is present, and the field has likely harvestable bolls with less than 350 heat unit accumulation present, treatment could still be justified for this pest.

Aphids and spider mites continue to be found with regularity in most fields. As cotton matures, these fields should be worth quick spot checks to:

  • make sure the aphids are not flaring to a level that could cause sticky cotton,
  • the mites will not be causing premature defoliation or robbing too much from the last of our boll development, or
  • that stink bugs are not coming in late to cause damage to our already made cotton bolls and the lint they contain.

Otherwise, the next major check for our program cotton will be harvest aid checks.

Corn

With our older scouting program corn either waiting on the combine or heading to the elevator, our younger were our only scouting concern. These fields ranged in stage from early dough to mid-dent.

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BGM turned out to be our primary concern again this week. Fields already treated for BGM issues look to be holding well with more than 3/4 of our late corn fields having been converted for silage or treated for the mite. The BGM are still present or building in the last 1/4 of our program corn to not be treated.

With the continued lack of moisture, these fields could very easily reach ET soon. Because so many of our replant corn fields are operated by producers with limited corn experience and the mites are remaining an issue much longer than usual, I should remind everyone that none of our labeled miticides can be considered ‘rescue’ treatments.

We need to understand how these products work and that they are not a quick fix. These products will take about 7-10 days to take effect. This is why our ET is only at 3.5 to 4 on our 0-10 Texas A&M AgriLife mite damage scale. If any of these treatments are applied to a population that is flaring harshly and are operating in colonies above the ear leaf in quantity, there might not be enough time for the miticides to work before the damage goes too far.

In all of our past and current miticide trials all of the labeled products are working well at labeled rates. All products are very safe on beneficials but take time to work and rely on those saved beneficials to finish off the mites. However, if these products are applied just a bit late, they will only slow down the mites before getting out of control and costing us yield.

We did note a few fall armyworms joining the usual bollworm, or corn earworm as it goes by in corn, engaging in some non-economic tip feeding. We also noted an increase in southern rust, in pockets, in a few fields. These fields might be in a race with the southern rust fungus. Which will happen first, ready for harvest, or disease at ET?

Sorghum

Our program sorghum ranged in stage from black line to 25% bloom this week. Our oldest fields are finally past economic insect damage in development but it did take both one sugarcane aphid treatment followed by a miticide treatment some weeks later to get them here. Hopefully the later sorghum will not follow the trend exactly.

Unfortunately, the rule pattern of SCA treatment continues. In this pattern for any field planted after April, as the field reaches boot to bloom, the SCA are flaring without exception. One by one, we have had to recommend treatment for the SCA. We only have a handful of the latest sorghum not treated yet.

For the SCA, the treatments are looking good and holding to date with any return or rebuilding SCA very hard to find. So far, the mite pressure has been less on the younger sorghum fields.

We are picking up sorghum midge in all blooming fields, but all at a sub-ET level with 0.18 / head being the highest this week. We are also picking up more headworms in sorghum in the form of bollworms, also at sub-ET levels with 0.46 small worms per head being the highest for the week. For note, this was a field in SE Swisher very near our Floyd moth trap with moth captures increasing to 211 moths this week but 0.08 to 0.2 worms per head are not uncommon throughout the program fields.

We are also picking up some Lygus and stink bugs in fields as the grain starts taking on color. Our highest Lygus counts were 1.25 Lygus per head and our highest stink bug count was 0.25 stink bugs per head. For both the Lygus and stink bugs, there were an assortment of varying species found.

Please consult our new guide for Managing Insect and Mite Pests of Texas Sorghum for exact thresholds and recommended treatments for all these assorted pests.

We also have a handy headworm threshold calculator available for any head-worm decisions.

I would still like to suggest that if you must treat sorghum for any head pests that you choose a product that will save your predators to aid in SCA control. We still cannot rely on predators alone for SCA control, but we cannot control SCA without predators.


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