June 19, 2007
It’s difficult to deal with something you’ve never experienced, but that’s the situation Georgia peanut producers are finding themselves in with this year’s drought.
“We are currently experiencing one of the most extreme drought situations in south
Georgia in more than five decades,” says University of Georgia Extension peanut specialist John Beasley. “We are already approximately 12 inches below normal in rainfall in most of our peanut producing area for the first five months of the year.
“It’s devastating on peanuts and all other crops in Georgia. Some are comparing it to the drought of 1954, but according to the records, at least farmers were able to get that crop planted, and the drought came later.”
The last crop report of May had Georgia’s peanut crop at 52 percent planted, and the original planting intentions called for about 500,000 acres. “Now, we’re hearing estimates of a 350,000-acre crop — it could be a record-low peanut crop. How much more will be planted is anybody’s guess,” says Beasley.
Georgia’s irrigated peanut crop looks “decent,” he says. “If we can get a good stand during the first 35 to 40 days of the season, we don’t need a big rain. Moisture is most critical when the plants start blooming. We’re encouraging our growers with irrigation not to over-water early in the season, especially with costs running at more than $10 per acre inch,” he says.
If a grower plants peanuts and a stand doesn’t come up until late June, there’s still a slim chance of making a crop, but it’s a risky proposition, says Beasley. “The best way to think of it is in the physiological development of peanut plants. It generally takes 30 to 35 days after emergence for bloom initiation. It then takes approximately 10 days for the peg to enter the soil and begin swelling after blooming. It then takes 85 to 90 days after the peg enters the soil to reach maturity.
“Using these typical time frames, we could make the following assumption. Let’s assume a field had complete emergence by June 25, then it would be about July 25 through 31 before we would expect bloom initiation. It would be about Aug. 5 through 10 before the first set of pegs entered the soil. Adding another 85 to 90 days means it would be about Nov. 1 at the earliest before the field would be at optimal maturity, probably even later. Cool or cold weather in October would stop the maturation process. Therefore, late June emergence would be a serious concern.”
Many growers, he says, are asking if they should try to continue producing a late-emerging crop — late June or later. “Please consult with your crop insurance adjuster as to the coverage and penalties that may exist for trying to finish out a crop on which a claim is made. Yield potential is greatly reduced when trying to make a crop on late planting or late emergence. In most cases, it is not worth the economical risk of trying to produce a late planted or late emerging crop.”
In response to the drought, members of the University of Georgia Peanut Team have released the following recommendations concerning various management practices.
• Dryland peanut fields should not be treated with a soil-applied herbicide if there is no chance for rain within seven days after application.
• Growers who must now rely exclusively on postemergence weed control programs need to pay close attention to what is going on in the field. Timely herbicide applications to small weeds will be more effective than waiting until more weeds have emerged and the drought lengthens.
• Weeds growing under drought stress will be more difficult to control due to thicker cuticles and a reduction in various metabolic processes.
• When applying postemergence herbicides, use the full labeled rate, apply in at least 15
GPA, and make sure proper adjuvants are used. If labeled, use a crop oil concentrate instead of a non-ionic surfactant.
Generally, several options are available for thrips control in non-irrigated peanuts. These include in-furrow systemic insecticides applied at planting, hopper box seed-treatment or foliar insecticides applied postemergence as needed.
The postemergence application as needed is the most prudent and viable option at this juncture in the season in view of the current and anticipated weather conditions. Even though thrips populations are highly variable across the peanut belt, they usually start declining in late May and early June, annually.
Also, thrips applications can be piggy-backed with other field operations as-needed. In the event we receive adequate rainfall for continued planting, growers can always revert to the other options, if preferred.
Lesser cornstalk borer should be anticipated with the current weather conditions. As a rule, it is not a standard recommendation to treat for lesser cornstalk borers before or at planting. Often we can withstand moderate populations of lesser cornstalk borers early in the season. If plantings are successful but low moisture prevails, we can anticipate in-season problems with lesser cornstalk borers at which time we can apply Lorsban at pegging. This is the most cost-effective way to attack the insect pest.
• Many peanut growers apply Temik 15G, 10 pounds per acre in the furrow at planting to reduce damage from peanut root knot nematodes. Adequate soil moisture is needed to activate the granules of Temik and to assure optimal control of the nematodes. Where possible, dry soils should be irrigated not only to insure vigorous germination of the seed but to also get the most benefit from the Temik.
• Aspergillus crown rot and Diplodia collar rot are peanut diseases that typically kill peanut plants that are in the seedling or early vegetative growth stages. Both of these diseases are most severe in hot and dry soils. Loss of plants early in the season helps to predispose the crop to increased damage from tomato spotted wilt. In the case of Aspergillus crown rot, hot and dry soil injures the tender seedling near the soil line, thus creating a wound easily exploited by the Aspergillus fungus. Best management tools for Aspergillus crown rot and Diplodia collar rot include the use of good crop rotation, a good fungicide seed treatment, management of lesser cornstalk borers, and judicious irrigation of dry soils, if possible. Additionally, research has demonstrated that use of Abound fungicide as an in-furrow application can help to reduce losses associated with both diseases when outbreaks are severe.
• Early and late leafspot diseases require moisture in the form of rainfall, irrigation or heavy dew to develop and spread. Adequate moisture is needed for spore germination and infection of the leaves. Moisture is also important for the development of spores on the leafspots. The mechanical force of falling rain and irrigation is an important mechanism to spread the spores and, thus, spread the leafspot diseases. Unfortunately, dry weather also reduces the growth of the peanut canopy, thus reducing the high humidity favoring growth of leaf spot fungi within the foliage of the plant. In periods of extremely dry weather, threat from leafspot diseases is greatly reduced. If dry weather continues, growers can likely delay the initiation of their leafspot fungicide program and extend the interval between fungicide applications. Also, in dry weather, growers may choose to use more of the less expensive protectant fungicides, such as chlorothalonil, in their programs as disease risk is lower. Peanut growers may wish to use the on-line version of the AU-Pnut leafspot advisory (www.AWIS.com) to help determine the timing of their fungicide applications.
• White mold is the most important soilborne disease that affects peanut producers in Georgia. White mold typically affects the crop once a significant foliar canopy develops. However, the disease can injure peanut plants at any stage of development. Spread of white mold is fueled by warm soils and moisture. This is especially evident as the white mold fungus spreads “like wildfire” as cottony growth within the canopy of a well irrigated crop.
In periods of drought, the spread of white mold, at least the common aboveground form, is drastically reduced as conditions are unfavorable for spread. However, growers must still remain vigilant as “underground” white mold can still wreak havoc.
Underground white mold can thrive where soils are warm and there enough moisture in the soil to allow growth of the fungus. Underground white mold typically attacks the pods and pegs and can be very difficult to detect.
• Cylindrocladium black rot can be devastating for some peanut producers. Although CBR occurs in many fields in Georgia regardless of early season conditions, the disease seems to be most severe when conditions are cool and wet at planting and when plants are young.
Such conditions facilitate the infection of the developing root system by the fungal pathogens. Conditions thus far in 2007 have been unfavorable for a general outbreak of CBR. However, the disease could be severe in specific fields.
• Rhizoctonia limb rot is favored by lush vine growth and ample moisture. If drought conditions continue this season, limb rot will be less of a problem except in fields with heavy vine growth as a result of irrigation.
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