|June 30, 2000
What a change! During June most producers received at least 3.5 inches of rain. The welcomed soil moisture resulted in a change of attitude by our producers and they responded by planting approximately 200,000 acres of cotton during the later part of the month. Now we have plenty of work to do trying to assist producers in making management decisions on a crop that has about 100 days to develop. Mistakes with this cotton crop will be very costly.
So far this crop has been challenged by seedling disease, wind erosion, crusting of the top soil, and lots of weeds. I have discussed each briefly. For further information visit the section on crop information on my web page ( http://sanangelo.tamu.edu/agronomy/ ).
Most of this acreage had to deal with less than favorable conditions. Cotton likes water but it doesn't like to keep its' roots wet.
I wouldn't be surprised if some of the producers brought in plants that look like these to the right.
Rhizoctonia (common names include Soreshin, Rhizoc, Damping Off) is the most common cause of post-emergence damping off throughout the world, Rhizoctonia invades the cotton plant at soil level. It produces a sunken lesion which girdles the hypocotyl (stem), causing the seedling to collapse. In wet conditions, the lesion can extend upwards several centimeters from soil line. Plants surviving Rhizoctonia are weakened and they bear the mark of the stem-girdling lesion at the base of the stem (Soreshin).
Contributing Factors: Excessive soil moisture predisposes cotton seedlings to infection by reducing their rate of growth. Infection occurs over a wide range of soil moisture levels.
Pythium (commonly known as Root Rot) infects the seed and radical, causing seed rot and pre-emergence damping off. The seedling hypocotyl (stem) can also be affected at soil line, causing post-emergence damping-off. At later stages of plant development, Pythium may cause stunting and chlorosis.
Contributing Factors: Pythium is most damaging to cotton seedlings at low temperatures and high soil moisture content. Degree of infestation is also impacted by soil texture and organic matter.
Thielaviopsis (commonly known as Black Root) is most prevalent in Texas, Mississippi, New Mexico, and the San Joaquin Valley area of California. Infection occurs at the seedling stage with roots and the portion of the hypocotyl below soil line rotting and turning black. When older plants are infected by Thielaviopsis the result is collar rot. Signs of Thielaviopsis include swelling/blackening of the tissue at the base of the stem and fungus growing from infection sites.
Contributing Factors: Thielaviopsis is more prevalent in clay soils than sandy soils and is usually most severe under cool, wet conditions.
When you get rain followed by quick evaporation, a crust will form on the soil surface. A producer will need to run a rotary hoe or some kind of tillage equipment over the field and break up that crust. He needs to do it as soon as possible and make sure the crust is broken and the soil aerated. The crust serves as an insulator, keeping the soil cool and damp. That can mean slow plant development and a greater risk of seedling diseases.
Anytime you leave a seedlings underground for any length of time, you end up with weak plants.
For the producers using hooded sprayers, for post directing the herbicide being applied, there are some 110 degree nozzles that produce large droplets. By installing these new nozzles in their hooded sprayer to the potential of physical drift of the herbicide solution is reduced.
This publication is made possible through Sorghum PROFIT, an initiative of the State of Texas as developed by the Texas Grain Sorghum Association in conjunction with the Texas A&M University Agriculture Program and Texas Tech University.
I have changed the basic layout of my web page to assist you in answering producers questions. I have assembled my links by crop subject matter where it can be accessed with the least amount of problem for you. In compiling this I found that some information was missing and publications had to be updated. Under the production topics of Cotton, Wheat and Grain Sorghum there are guides for producing those crops in West Central Texas.
The search engine on cotton is very helpful. Unfortunately, the same type of information search is not available for the other crops. The cotton search engine looks up information on cotton from university and government web servers only. That keeps you from having to wade through a bunch of unwanted information.
The "Weed Identification and Control" listing under production, links you to web sites across the USA. I still plan to build a local weed information ID site to address weeds we deal with. Your help in securing pictures of weeds will be appreciated.