Saturday, June 3, 2017

South-West Plains IPM Update Volume 17, Issue 5

GENERAL CONDITIONS:
           
              Cotton planting is still underway, although planters are stopped in some areas thanks to much needed rain. Although they were widespread, much of the area received much needed rain, especially our dry land fields. Cotton ranges from still in the bag to 1 true leaf is the fields I am checking.  Insects are moving into young cotton plants as our pastures become drier, and our winter crops are harvested or terminated. Additionally, I have found a few aphids in cotton outside of Plains this week.
               Peanuts are moving along well, and there are no big issues in peanuts yet. Over the last 7 days I have started to notice more wireworms and white grubs in area peanut fields. Foliage feeding worms were found in one peanut field in Yoakum County and one in Terry County, these populations are still well below the threshold and is a sign that we need to begin looking for them in our fields.


COTTON:
             
               Local cotton fields range from just planted to 1 true leaf. Thrips are starting to be found in cotton fields that I am scouting this week. These populations are well below the 12 plus thrips per plant that Blayne Reed, Extension Agent-IPM for Hale, Swisher, and Floyd Counties, is seeing in his cotton fields. One field in Yoakum County was starting to have immature thrips show up, and this is a sign that our insecticide seed treatments are playing out. As our seed treatments play out we need to keep our eye on the thrips population in our fields, to minimize the damage caused by thrips. In last week’s newsletter, I discussed identification (Figure 1-A), damage (Figure 1-B), and ways to manage thrips.

               I am seeing fields with poor stands, and hearing reports of fields needing to be replanted. Most of these fields were planted before the 17th of May, or are dryland fields that had enough moisture to start the germination process, but thanks to the hot temperatures and high winds last week (May 21-27) top soil moisture depleted before the crop could emerge. Cotton can overcome some stand loss, but if fields get below 1.5 seeds per foot in our area we can see a decrease in yield. When determining when to replant we need to weight the cost of replanting against the benefits of replanting. As we get deeper into the month of June the potential yield of replanted fields are reduced and you may be able to yield the same without replanting the field.

PEANUTS:

             Peanuts are growing nicely, and some of our earlier planted fields are starting to set root nodules. As we are now at the point where some of our fields are reaching 4 weeks since planting we need to start evaluating our inoculant program. By evaluating our inoculant program, we can determine if we need to apply mid-season nitrogen to our peanuts. To evaluate our nodulation, we need to get an average number of nodules per plant across the field. This can be done by checking 1 site for every 10 acres of peanuts, and digging up 3 row feet of plants, count the total number of nodules, and dividing by the number of plants at that site. For example, at 1 site we count a total of 240 nodules, at that site there were 12 plants in 3 row feet; at this site, the average nodules per plant is 20 nodules. Ideally, we would like to average 16 or more nodules per plant. If we get below 16 nodules per plant a mid-season nitrogen program would help reach our expected yields (Table 1). If a field is averaging 10 or fewer nodules per plant we also need to investigate why our field did not nodulate as expected.  Some common reason our inoculation programs fail include: exposure to high temperature (especially above 90 F), exposure to direct sunlight, mixed with chlorinated water, improper placement of inoculant in the furrow, using low rates of inoculant, planting shallower than an inch and a half, inoculant was not compatible with other in furrow products, placing large amounts of N fertilizer in furrow, and using old or expired inoculum.

              
                 I am still seeing thrips and wireworms in area peanut fields. This week I have also started seeing white grubs and foliage feeding worms. White grubs are the larvae of June beetles, are white with a reddish-brown head, and when found in the soil are curled up in a c-shape (Figure 2). This insect early in the season will feed on secondary roots reducing the amount of water and nutrients the plant can absorbed by the plant, and during pod set and fill can be found feeding on the pods often times eating the all the kernels within the pod. There currently are no effective insecticides for white grubs, and it is recommended heavily infested fields be dug early to avoid Seg. III (aflatoxin contamination) issues at the buying point. 

Foliage feeding worms include numerous insect species, some which occur in other crops around the area (Figure 3). Common foliage feeding worms in the area include cabbage loopers, velvet bean caterpillar, yellowstriped armyworm, and occasionally corn earworm/bollworm. These insects primarily feed on the leaves of the plants, but occasionally can be found feeding on pegs. Peanut plants can tolerate a good amount of defoliation from foliage feeders, but extensive defoliation from these insects can lead to yield loss. There are economic thresholds set for foliage feeding worms in peanuts, and include 10-12 worms per a row foot in runner type peanuts and 6-8 worms per row foot in Spanish peanuts. However, if the worms move down in the canopy and start clipping pegs off, treatment may be justified before they reach the current threshold. Insecticides labeled for control of foliage feeding worms include the active ingredients Chlorantraniliprole, Esfenvalerate, Lambda-cyhalothrin, Methomyl, Acephate, Carbaryl, Indoxacard, and Spinosad. When deciding to spray, we also need to make sure we protect our beneficial insect population, so we do not flare secondary pests like spider mites.


Thank you to all the sponsors of the South-West Plains IPM Program. The sponsors of the program for the 2017 growing season are below.

Platinum Sponsors:

Gold Sponsors:
Doyle Fincher Farm
Golden Peanuts and Tree Nuts

Silver Sponsors: 
Birdsong Peanuts

Bronze Sponsors:
Crop Production Services
New-Tex Gin, Inc. 





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