Planting Delays and Pigweed Control

It almost goes without saying that weather conditions over the past few weeks have delayed cotton planting.  Some growers in the south Delta will likely begin planting operations where field conditions permit over the weekend.  However, a 50% chance of rain is forecasted for most of the Delta sometime between Sunday and Tuesday.  In terms of planting cotton, some growers are behind where they usually are this time of year.  Further complicating this issue is that many are behind on planting and/or fertilizing other crops.  In addition, for those along the river, seep water is causing additional problems and delays.  We are on the verge of planting late and if we receive additional rainfall early next week we will be late.  Historically, mid- to late-April through May 15^th is the prime window for planting cotton.  Generally, yields of cotton planted after May 15^th are lower than that of earlier planted cotton.  Weather conditions in northeast Mississippi have not allowed some producers to begin planting corn.  Research data from northeast Mississippi indicates that corn planted after May 5^th will likely yield less than corn planted in a more timely manner.  If weather conditions delay planting next week, it may be wise to consider planting additional cotton in place of corn in northeast Mississippi.

In addition to delayed planting due to weather conditions, fields should be carefully scouted for pigweed emergence even where pre-plant herbicides where applied.  Excessive soil moisture has not only delayed planting, it has also delayed herbicide applications that would have went out behind the planter.  If any pigweed are emerged when the planter goes through the field, paraquat plus a residual material should be applied immediately after planting.  When dealing with glyphosate-resistant pigweed, once the pigweed has emerged and the crop has emerged, pigweed control in Roundup Ready Flex® cotton becomes very difficult.  Often times these populations are also tolerant to ALS-inhibiting herbicides including Envoke® and Staple®.  Essentially the remaining options for control are plowing, chopping crews, or hooded sprayers.  If you are planting Liberty Link® cotton, Ignite is effective for control less than 3-4” tall.  It should also be noted that residual herbicides are as important in a Liberty Link® system as they are in a Roundup Ready Flex® system.  Mississippi State University recommendations for pigweed control can be found at the following address:

Cotton:

http://msucares.com/crops/weeds/herbshort_amapa_cot_09-28-10.pdf

Soybeans:

http://msucares.com/crops/weeds/pigweed.pdf

Corn:

http://msucares.com/crops/weeds/herbshort_amapa_cor_09-28-10.pdf