Texas Plains Pest Management: Insects Still Active but Few Passed Threshold

    Bollworm eggs on cotton leaf.

    General Status

    Last week I would have stated that our crops are looking like some pretty good mid to late July fields, despite it being August. Now things are a bit more confusing, and it has been quite some time since we had a good rain shower. It never seems to fail in West Texas that right when our crops need moisture help the most, none is available.

    Most of our dryland cotton fields, after a wonderful if late start, have raced to absolute cut-out after just a few weeks of blooming. These have been holding as much fruit as moisture allows but the door is about to slam shut on any benefit from additional rains for these fields in a mater of days.

    Most of our irrigated cotton is in peak water use and rushing to cut-out quickly despite ongoing irrigations and being growthy just a few weeks ago. It seems quite the tight rope act to keep these fields setting harvestable bolls while not pushing fields so hard they overshoot the upcoming landing. Then we still have fields that need a bit of burn to slow them down in time, but that still presents the risk of loosing potential fruit to stress.

    The largest portion of our late corn has been pollenating and starting kernel fill during while the bulk of our sorghum is blooming and filling grain, both representing peak water use, during this dry period. Meanwhile the insects that built on the lush vegetation earlier are looking for suitable hosts and our typical seasonal pest seem to be settling in.

    Cotton

    Our most advanced cotton fields might not be our most mature cotton fields this week. We have had our dryland field reach absolute cut-out of 3.5 NAWF or less after just a few weeks of blooming. I am concerned about the boll load and fill here but there is no management decision or input we can make that can help as this is water related.

    We also had some of our most advanced irrigated field reach this developmental milestone also, but under much healthier conditions and boll load. Our latest fields are still coming in at 7.5 to 6 NAWF with just some of their first bolls being made or are starting to get rank.

    AgFax Weed Solutions


    In some of these rarer cases, initiating a bit of stress by withholding irrigation water or a heavier PGR use can be justified but without help from rainfall, it is a dangerous line to walk before too much stress is added and yield cut to less than it could have been. We are making field by field recommendations and decisions based on all the information available and each field is unique in needs, but water is a key factor now.

    We are still finding more bollworm eggs than we have seen in the past few years, but when we are finding them, we rarely see more than 3,000 to 6,000 per acre so far. We also have no major worms that have developed from them the eggs yet, or at least very few that have survived.

    We have a pretty healthy beneficial population that have been cleaning up the very light but persistent cotton aphid presence in field. They have certainly been able to control such a light bollworm emergence in cotton so far. Our highest worm populations have been below 2,000 per acre with most fields returning with zero worms found.

    Our ‘usual’ bollworm peak (if we have one) is still in front of us and we should remain vigilant as long as we have harvestable bolls susceptible to bollworms in all Bt technologies. We are still finding a very light to light foliage feeding worms, mostly true armyworms, and cabbage loopers in most non-Bt fields not causing much damage.

    We had a slight in-crease in Lygus this week, but still most fields are returning with none found. Stink bugs continue to turn up fairly regularly in our data sets at sub-economic levels. We might need to stay alert a tad longer this fall on the watch for these stink bugs. They tend to cluster late in the year and can cause serious damage and rot to older bolls as they mature out.

    Corn

    Our youngest PPM corn is at V10 while our oldest is in solid dent stage, but the bulk of our corn is now in silk to blister. Pests remain light but we are noting an overall increase in pressure that still remains far below ET. The Banks grass mites are receiving ratings of 0.5-2 on the 0-10 dam-age rating scale with 3.5-4 being ET.

    Corn earworms (cotton bollworm) are moving into the younger tasseled corn quite readily, but they should not be an economic concern baring some extreme circumstances. Due to the staging of our corn, and the preference of bollworms for corn, much of our bollworm pressure that could be put on our area cotton, might be harmlessly directed to these later corn fields.

    We are noting some fall armyworms among the earworms, but they only represent a small percent-age of the pressure, and all feeding remains on the silks and at the tip so far. Common rust increased slightly again this week but still remains a light concern

    Sorghum

    Our oldest program sorghum is in dough stage while our youngest is at V8, but we have just about every stage in between in our scouting program which includes several fields in bloom. The big news remains the sugarcane aphid (SCA). I am averaging 2-4 phone calls per day from producers, elevator personnel, company reps, and media about this pest.

    The area is very alert to the volume of late sorghum we have, the number of producers who have not grown sorghum since the aphid’s arrival, and the fact that the aphid can be found in all fields at some level. While I expect to eventually treat 100% of our fields, this one-time monster of an invasive is behaving much more like a common, but respect demanding ‘normal’ pest.

    Nature seems to have found a good balance with beneficials truly checking the SCA increases. The life sucking explosion of aphid increases this aphid is capable of looks to be slowed again this year. We finally treated our first field for SCA as the beneficials held their ‘explosion’ to a general increase.

    While the predator population we are seeing in sorghum right now is remarkable, it does not look strong enough to hold the aphid below ET indefinitely and we will be counting on those same beneficials to finish the aphid off post treatment. I expect to be managing fields along our Texas High Plains threshold guidelines and recommending treatment as needed.

    Those guidelines are 30% plants infested with a sizable colony ET for post boot sorghum and 20% for pre-boot sorghum. It is still hard to find these aphids in our whorl stage sorghum, but easier to find in all post boot fields.

    The SCA are not the only pest we have in our area sorghum, but it is the only one we had to treat for this week. We are still finding headworms of both bollworm and fall armyworm types and a few sorghum midge. All of these head pests were actually lighter this week than last with no field having more than 0.4 worms per head and most without any.

    We started finding a few Lygus and stink bugs in dough or later stage fields this week. Our best estimate based on limited research indicates that it could take as many as 10-14 Lygus per head to be an economic threat at this stage. The stink bug threshold should be around 4 per head. Our highest level for either of these pests were 0.16 per head this week.




    The Latest


    Send press releases to Ernst@Agfax.com.

    View All Events


    Send press releases to Ernst@Agfax.com.

    View All Events