The latest U.S. Drought Monitor shows that 99% of Colquitt County is classified as abnormally dry. The cotton and peanut crops are reaching peak irrigation demand and a good rain is needed. Insect pressure has been variable in both cotton and peanuts. Whitefly populations are increasing in local cotton fields. Corn harvest began last week.
Cotton: The cotton crop in Colquitt County ranges from the squaring stage to full bloom. Whitefly populations have increased over the past couple of weeks, and growers should continue scouting fields for developing infestations. Fortunately, the cotton jassid situation has remained relatively quiet throughout the county. If you are interested in viewing the latest cotton jassid distribution map from EDDMapS, it is provided below.
Tankmixing Grass herbicides with fungicides on peanuts. This has been a common question. According to Dr. Eric Prostko, for optimum grass control, it not a great idea to mix POST grass herbicides with a fungicide due to the increased potential for antagonism. Generally, Abound, Bravo WS, Headline, and Folicur have all reduced grass control at some point when tank-mixed with POST grass herbicides. When a grass/fungicide interaction has occurred, grass control has been reduced by as little as 3% (Poast + Bravo WS – large crabgrass) or as much as 45% (Select + Bravo WS – large crabgrass). It all depends upon the grass species and fungicide used.
Sorghum: I have been getting a question or two about aphids in grain sorghum. According to the publication Sorghum Insect Pests and Their Management, predominant aphids attacking sorghum in Georgia are sorghum aphid (Melanaphis sacchari), corn leaf aphid (Rhopalosiphum maidis), and greenbug (Shizaphis graminim) and the Yellow sugarcane aphid (Sipha flava). The figure below shows the aphids found on sorghum.
What are the aphid thresholds for sorghum? According to the UGA Pest Management handbook the thresholds for greenbug, corn leaf aphid and sorghum aphid is as follows.
GREENBUG: Treat when greenbugs are present and killing 3 leaves/
plant before boot stage.
CORN LEAF APHID: Treat when a large population occurs and leaves are dying.
SORGHUM (FORMERLY SUGARCANE) APHID: In general treat when infestations reach 40 aphids/leaf OR when pre-boot stage 20% of plants are infested and large numbers are present. Good spray coverage is critical, minimum of 10 GPA by ground and 5 GPA by air.
Control options for aphids are below.
Rust in the bermudagrass!
This past week, I began seeing leaf rust in local bermudagrass fields. Leaf rust, also known as Puccinia disease, is caused by Puccinia cynodontis. The disease typically appears in late summer when temperatures range from 75°F to 90°F and relative humidity is high. Heavy infestations can reduce both hay yield and forage quality.
In bermudagrass hay production, there are currently no fungicides labeled for the management of foliar diseases. There are five management practices that are effective in decreasing risk of disease infection including: selecting a resistant bermudagrass variety, maintaining soil fertility, managing irrigation, removing thatch and harvesting forage in a timely manner.
If you would like more information about this subject please go to the following blog post “What is wrong with my bermudagrass hay field?”
What moisture level does my hay need to be?
The weather over the last week has been challenging for hay producers, and hay moisture has been a topic in several conversations. Most research indicates that round bales should be baled at a moisture content of 15% or less, while square bales should be kept below 17%.
Even when hay is baled at the target moisture level, bale temperatures may increase during the first two to three weeks after baling. When grass is first cut for hay, it is not actually “dead.” Plant cells within the forage continue to respire, burning plant sugars to produce energy and releasing a small amount of heat. Some refer to this process as going through a “sweat” because moisture is driven off and the forage eventually reaches a stable moisture level of about 12%.
During this phase, bale temperatures often reach as high as 120°F. The amount of respiration and heat generated depends on the moisture content of the forage at baling.
If forage is baled above the target moisture level, bale temperatures can increase substantially. Once temperatures exceed 140°F, sugars begin to caramelize and protein quality declines. The protein can become so damaged that it is rendered indigestible and, in extreme cases, animals may become protein deficient. Interestingly, heat-damaged hay is often readily consumed because the caramelized forage is highly palatable.
If forage temperatures exceed 180°F, the hay may be at risk of spontaneous combustion. If temperatures reach 200°F, contact the fire department at once and do not move the hay, as moving it introduces oxygen and increases the risk of fire.
If a hay thermometer is not available, drive a piece of rebar or a steel rod into the center of three or four bales. Check the rod several times a day. If it is too hot to hold comfortably, bale temperatures are likely above 140°F. If the rod is extremely hot, contact the fire department and do not move the hay. Below is an interesting article from the UGA Forage Team on this subject.
If you have questions, please contact your local County Extension agent.
Have a great week,
Jeremy M. Kichler
Colquitt County Extension Coordinator
The University of Georgia Cooperative Extension does not endorse or guarantee the performance any products mentioned in this update.