These conditions and early cotton insect problems were answered recently by Pitts in a report that can be found online at the NTOK Cotton website, ntokcotton.org.
In summary, Pitts had this to say about the effects of soil temperatures on cotton: "We are starting to see some fields with fully emerged cotton and some that are just breaking the soil surface," he said. "Some growers are asking about stands and what to do. If you see roots with big shanks or swollen areas or dead growth tips, then cold chiling has occurred."That cotton was probably planted on May 2-4, 2010,"
Pitts asks growers to check his comments in his May 6, 2010, newsletter at the above website.
"In addition," he said, "Cold chilling makes the plant more vulnerable to disease so a higher incidence of disease may occur on cotton planted before and after the dates listed here. The plant can go ahead and grow, but will have a root system with less than desirable growth."
Pitts says decisions on replanting cotton should be based on fields that have seedlings with no cold chilling. "If your field has escaped that type of damage, but had a low emergence due to crusting or other physical issues, it is generally acceptable to have a stand of only two plants per foot of row on 40 inch planting.
"Decisions on replant should be based on fields with plants with no cold chilling. If your field has escaped that type of damage, but had a low emergence due to crusting or other physical issues, it is generally acceptable to have of only two plants per foot of row on 40 inch plantings. With current forecast, plantings after May 15 should be fine as no nighttime temperatures below 60 degrees are predicted. Also, historical temperature data show average lows do not occur beyond this date."
With some fields varying from emergence, Pitts said, thrips activity needs to be monitored on a regular basis. Heavy thrips migrations are currently occurring on border crops and where weeds dry down and mature. Prolonged migration can occurr for fields next to wheat and pastures.
Keep a careful watch on these areas, Pitts said. Fields like this that were treated with an at-plant systemic or seed treated insecticide may show signs residual effect is wearing off.
These fields need to be monitored closely as heavy infestations may destroy plant terminal buds, he said. Treatment is advised when the number of thrips averages one or more per true leaf present.
Be careful to watch fields where plants are struggling, Pitts said. Orthene or Bidrin should be used and will tank mix well with glyphosate.
When scouting fields, remember thrips and wind damage can be confused with each other, Pitts said. An insecticide is rarely justified if plants are at the five-seven true leaf stage or when plants begin to square.
Pitts works at the OSU Southwest Research and Extension Center, 16721 S. US 283, south of Altus, Ok. He can be reached at 1-580-482-8880 or 580-318-3121. His email is firstname.lastname@example.org.