SOYBEANS. August 2009

Transcription

1 Field Crop Newsletter August 2009 SOYBEANS Melissa J. Evans Extension Agent, Agriculture Field Crops Contact Us: NCCE-Onslow County 4024 Richlands Hwy. Jacksonville, NC (910) (910) Fax edu PEST MANAGEMENT Crop scouting has been used for many years to help identify pest problems and determine what action, if any, should be taken. However, scouting is only one part of an overall approach known as integrated pest management (IPM). The objectives of integrated pest management are to consider all appropriate methods of lowering pest levels, to use pesticides only according to need, and to help produce crops more profitably. The use of proper scouting procedures and knowledge of economic thresholds can ensure that growers use pesticides properly and realize maximum returns for their investment. Scouting The purpose of scouting your fields is to obtain an objective summary of the pest situation. Some of the information obtained will be useful in making immediate pest control decisions. Other observations will help in knowing what to expect at a comparable time next year. Sampling locations in a soybean field should be chosen in a way that will accurately represent actual pest conditions throughout the field. Specific sample site should be selected on the basis of a predetermined random pattern, such as the one below. North Carolina State University and North Carolina A&T State University commit themselves to positive action to secure equal opportunity regardless of race, color, creed, national origin, religion, sex, age, veteran status or disability. In addition, the two Universities welcome all persons without regard to sexual orientation. North Carolina State University, North Carolina A&T State University, U.S. Department of Agriculture, and local governments cooperating.

2 There are several points to remember when scouting a field: 1. Select stops on a representative basis. Do not fall into the habit of entering the field at the same place each week. 2. Walk to within 50 feet of every border, many times pests will invade the borders more readily than the entire field. 3. As you take samples, observe plants surrounding the sample site. 4. After obtaining counts and estimates, determine whether action is necessary. 5. If you find a pest you do not recognize, take samples to your local county Extension agent for identification. The number of stops to make depend on the size of the field. The following chart gives the suggested number of stops for various field sizes. Field Size Number of Stops (acres) Insects Weeds up to over 50 Split into two fields Foliage-Feeding Insect Thresholds Different treatment thresholds are used during the vegetative and reproductive stages of plant growth. Before soybeans bloom, they can tolerate 30 percent loss of foliage. However, a foliage loss of 15 percent is used as a threshold beginning two weeks before bloom and throughout the blooming and pod-filling stages. Pod-Feeding Insect Thresholds Pod-feeding insect thresholds apply to soybeans during the blooming and podfilling growth stages. Corn Earworms The threshold used depends upon the row width and the sample device used. In 30-inch to 40-inch rows sampled with the standard shake cloth (best sheet), use an action threshold of two earworms (3/8 inch or longer) per row foot. Narrow rows sampled with a rigid beat cloth or sweep net will require one of the following action thresholds: Sampling Row #Rows Threshold Device Width per (inches) sample Rigid beat Cloth Sweep net Stinkbugs Stinkbug thresholds are one-half the corn earworm thresholds given in the table above. SOYBEAN RUST UPDATE An up-to-date map of where rust has been found is at The current version of these NC updates should also be available at the NCSU Tele-tip line at Using Litter as Fertilizer Many producers in the area are utilizing turkey litter for a fertilizer to reduce input costs. Although this is a great source of nutrients and organic matter that can help reduce your fertilizer bill, there are a few things to keep in

3 consideration. First, turkey litter can vary in its analysis. Depending on how or where your litter is stored after being removed from the house can greatly affect the nutrient availability in the litter. Litter is most valuable immediately after it is removed from the house, however nitrogen can be preserved if stored in a shed or deep pile that is covered. Litter should never be stored outside and exposed to the weather! If it is stored outside it should be temporary. When litter is stored outside and exposed to the weather, nutrient losses can begin to occur reducing the value of the litter. If you applying litter to your fields make sure you have it tested so that you will know that nutrient content and availability. In order to have it tested all you need to do is to take a representative sample of the litter pile or house, much like taking a soil sample. Be sure to fill a sandwich size Ziploc bag with the litter, which will be enough for the test. The Cooperative Extension office has the necessary forms that must be filled out. The basic test cost $5.00. Palmer Amaranth Palmer Amaranth is a member of the pigweed family. It is summer annual which can reach up to 6.5 feet tall. It resembles other pigweeds; however it has some varying features. Palmer Amaranth has hairless leaves with prominent white veins on the underside of the leaves. The leaves are alternately arranged on long petioles (Figure 1). The seedhead also differs from other pigweeds (Figure 2). The female plants have spines whereas the male plants do not. The taproot is often a red color. Figure 1 Figure 2 It has always been troublesome weed in many crops, especially cotton. With the introduction of glyphosate tolerant crops, the problem was lessened. Recently, the problem has resurfaced due to the widespread occurrence of glyphosate-resistant biotypes of the weed. This problem becomes more worrisome since Palmer Amaranth has already been confirmed to be resistant to other herbicide mode of actions. These include triazines such as atrazine. ALS inhibitors, and now glyphosate. In North Carolina, all three of these resistances can be found. It is also feared that without proper stewardship of our PPO inhibiting herbicides this mode of action could be next on the list of resistance.

4 If glyphosate resistance is suspected, the best management practice is to apply a preemergence herbicide such as fomesafen, pendimethalin, atrazine or s- metolachlor. Depending on your cropping system, you will then be able to determine your herbicide selection. The main concern is developing PPO resistance in this weed, so we encourage producers in limit PPO inhibitors to one application per year. This would include herbicides such as Valor, Valor XLT, Aim Reflex, Reflex, Resource, Prefix, Envive, Blazer, and Flexstar. This is not a complete list, but includes some of the more popular choices. If you have a question about whether the mode of action of a herbicide is a PPO inhibitor and unable to find the information on the label, contact the local extension agent. This practice will hopefully limit the selection pressure put on this mode of action so that we can continue usage of PPO inhibitors on Palmer Amaranth. Important Note: If you think the plant may be resistant DO NOT LET IT GO TO SEED! The female plants can production between 400 to 500,000 seeds per plant. Upcoming Events Pesticide V Training August 6, pm-7pm At the Extension Office Please RSVP to Nita Walton by Aug. 4th Flue-Cured Tobacco Field Day August 13, :30pm-8:00pm 2200 Hwy 222 W Kenly, NC Please RSVP to the Wayne Co. Extension Office by August Pesticide X Training August 20, pm-7pm At the Extension Office Please RSVP to Nita Walton by August 18th Pesticide X Training August 26, am-12pm At the Extension Office Please RSVP to Nita Walton by August 24th SPOTLIGHT ONSLOW COUNTY BEEKEEPERS ASSOCIATION The Onslow County Beekeepers Association was organized January 14, 2003 to promote beekeeping and increase the skill level of area beekeepers through cooperation and education. Monthly meetings are held the second Tuesday at 7:00 9:00 pm at the Onslow County Multipurpose Complex. Meetings are open to area beekeepers and persons interested in learning about beekeeping. A short course which teaches basic entry level beekeeping skills is conducted at the Multipurpose Complex in November each fall for a nominal fee. Contact the Cooperative Extension office at to enroll for the course. The Onslow County Beekeepers Association maintains an active membership of members who are actively involved in promoting beekeeping through area schools, the county fair, festivals and public events. Individuals needing assistance with honeybee swarms or advice on how to deal with honeybees in structures can contact Jeff Morton with the Cooperative Extension office at (910)

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