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Due to the 4 th of July holiday there will be no newsletter next week. We will continue the week of the 9 th .

Rootworm School at HAL

Ever wonder how your rootworm control methods worked, or if you are seeing rootworm damage in your rotated corn? On Tuesday, July 24 th , we will be having a Rootworm School at the Haskell Ag Lab in Concord. Learn how to identify damage from rootworm larvae, rate roots, and differentiate damage from other possible causes. This ½ day event will be in the afternoon. For more information call Keith Jarvi at (402) 584-3806, cell (402) 649-7347, or Pat Bathke (402) 584-3837. Because of space limitations, the first 25 people who register by contacting Keith or Pat will be accepted. There will be a $10.00 registration fee for refreshments and materials.

Western Bean Cutworm

Western bean cutworm moths are being caught in our light trap at Concord . Numbers up to now have been low, but we have not yet reached peak flight. As moth numbers increase, mating will commence and the females will begin to lay eggs on corn. The appearance of the first moths provides a signal that farmers and crop consultants should begin to scout fields for the white, dome-shaped eggs. Western bean cutworm moths lay eggs in clusters of five to 200 on the top surface of the upper most leaf of a corn plant and on any leaf surface of dry beans. The eggs require five to seven days to develop, during which time the egg color changes to tan and then to purple immediately before they hatch.

After the small, dark brown larvae hatch on corn plant, they move to the whorl or tassel to feed on the tender yellow leaf tissue or on the tassel itself. Once the tassel emerges or if it has already emerged when the eggs hatch, the larvae will move to the green silks. The developing larvae will feed on the green silks moving down the silk channel until they reach the ear tip. The larvae will feed in the ear tip until they are fully developed. If the infestation on one ear tip is so great that the larvae become crowded, a few individuals may move outside the ear and begin to feed on the side of the ear.

Even though field scouting for western bean cutworm in field corn should begin when the first moths are caught, control decisions should be made shortly after the moth flight peaks. The moth flight usually peaks in early-mid July. When scouting for western bean cutworms in corn, check 20 plants in at least five areas of each field. Look for eggs on the top surface of the upper most leaf or look for larvae in the tassel. If 8% of field corn plants, 5% of seed corn plants or 5% of popcorn plants have egg masses or larvae, consider applying an insecticide. Herculex varieties appear to control the larvae very well, although not perfectly, and should not need treating.

Western bean cutworm moths prefer to lay eggs in corn plants that are in the late whorl stage compared to those that have completely tasseled. Pay particular attention to later planted fields or those with uneven development. Western bean cutworm eggs that hatch when corn plants are in the whorl stage of growth have a high rate of survival. The larvae are well protected in the whorl or tassel.

If an insecticide treatment is warranted in corn, it should be made when 95% of the plants in a field have tasseled. This timing of the application increases the chance that the worms will be exposed to the insecticide resulting in better control. Chemigation has provided very good control of this insect, even at lowest labeled rates. Asana, Ambush, Baythroid, Pounce, Lorsban, Capture, Mustang, Penncap-M, Proaxis, Warrior, and Seven are all labeled for control of western bean cutworm. Many generics are also available that will give good control. A list of registered insecticides, rates, preharvest intervals, and grazing restrictions can be found at http://entomology.unl.edu/instabls/wbeancut.htm

Integrated Management of Eastern Red Cedar in Grasslands of Nebraska

History and Biology - Eastern red cedar ( Juniperus virginiana L.) is one of 13 juniper species native to the United States. It is the most widespread tree-sized conifer and is native to every state east of the 100th meridian. Throughout this vast range, eastern red cedar grows on many soils and under varying climatic conditions. This adaptability has enhanced eastern red cedar's recent spread into areas where it was formerly rare or absent. Eastern red cedar is a dioecious species, which means individual trees are either male or female. Starting in the 6 th or 7 th year of growth, female trees produce small, berrylike fruits that are eaten by many birds and some small mammals, which indirectly helps spread the seed via droppings. Digestion actually improves germination.

Impact of eastern Red Cedar - Eastern red cedar is a problem on grasslands primarily because it reduces forage production and livestock handling. Developing trees alter the microclimate, which encourages a shift from desirable warm-season native grasses to introduced cool-season grasses such as Kentucky bluegrass. Heavy infestations make livestock handling more difficult. All these adverse effects can be reflected in lower rental rates or sale prices for infested grassland. Established infestations usually get worse over time due to continued seed production, and established trees get bigger, thus shading the grass beneath even more. Eventually near total coverage by eastern red cedar can be expected, resulting in total loss of grass production. Control measures should be initiated as soon as possible, both to improve effectiveness and reduce total control costs.

Integrated Management of Eastern Red Cedar - Integrated management has been commonly described as “a multi-disciplinary approach utilizing the application of numerous alternative control measures”. In practical terms, it means developing a management program based on a best method, or a combination of methods for the particular site, which could include mechanical, biological and chemical practices.

As previously described, Nebraska 's eastern red cedar infestations have developed over several decades. Likewise, management of these infestations is best viewed as a long-term or on-going effort, both to reduce the initial infestations and prevent them from redeveloping to economically damaging levels. It is best to begin treatment as soon as possible, once treatment has begun considerable time is gained to continue long-term management. The emphasis should be on management of the infestation, rather than eradication. Eradication is not economical, and probably not physically possible in most cases. Instead, it should be recognized that some remaining larger trees, which are the most difficult and expensive to kill, do little damage. In fact, at low levels, eastern red cedar can be viewed as a potential resource, providing livestock shelter, wildlife habitat, timber products, and aesthetic values. Most important, long-term selective management is considerably less expensive than a more intensive, short-term approach.

If the goal is to just reduce overall number of trees and stop further spreading (e.g. management of wildlife habitat), it is recommended to cut female trees only. Female trees are the ones that produce berry-like fruits. This would allow “male trees” to grow and provide much needed cover for wildlife, or land beautification, while reducing further spreading.

Manual and Mechanical control - Manual and mechanical control involves methods such as digging trees, cutting and mowing. It is very effective for small areas, and it is most efficient on trees up to 2 feet tall.

Cutting is an effective method of control because eastern red cedar does not sprout. Trees cut below the lowest branches will not regrow. A variety of handheld or motor-powered cutting tools can be used. Hand-held tools (shears, saws, spade, shovel, heavier hoe) are effective on small trees (< 5 ft tall), while larger trees require a chain saw or vehicle-mounted shears. The equipment varies from tractor pulled PTO driven shredders to hydraulic drive devices that mount on skid steer loaders. Most of the shredders can easily handle up to 3-4 inch stem diameter trees, while some can cut trees up to 15 inches. In general, cutting is a method that can be time consuming and labor intensive. Cutting alone also fails to remove all of the problem because fallen trees continue to occupy space. Thus, all cut trees should be gathered and burned, or permanently removed from the grassland. Mowing of short trees (< 3 ft tall) can be conducted using a shielded mower shortly after regular cutting and haying.

Biological control of eastern red cedar - Biological control is the use of natural enemies to reduce weed populations to economically acceptable levels. In the case of red cedar control, goats can be utilized as an effective bio-control agent for trees that are up to 3-4 ft tall. Experience from Nebraska suggest that most cedar trees < 24 inches tall were killed by goats utilizing a paddock grazing system. The control level was reduced by 50 percent on trees 4-8 feet tall trees, however the goats managed to defoliate bottom branches and strip bark from branches and trunks up to three inches in diameter.

Generally, goats are browsers with diets consisting of about 70% of non-grassy species, which indicates that they should not compete with cattle for grass. Goats prefer non-grassy species, but they would eat grass if no other species are available. This also suggests that goats in general can help in controlling many plant species that cattle do not eat, including various noxious weeds (e.g. leafy spurge, thistles). Goat production can be also a profitable livestock enterprise that provides income through meat and milk production, and leasing fees for goat leased to control various invasive forbs and shrubs. Important factors in managing goats include the use of appropriate stocking rates and quality fencing. In essence, the number of goats needs to be adjusted to the amount of plant material needed to control.

The grazing strategy with the goats should vary depending on the management goals set for the pasture. Adding one or two goats per cow and letting the goats and cattle run together is an excellent maintenance strategy for pasture with a moderate to low cedar infestation. However, if the goal is to get a quicker response and try to suppress denser stands then the area needs to be fenced off using temporary fencing. The per acre stocking rate should be at least 10 goats/acre of land infested. This stocking rate with moderate cedar infestation should result in significant damage to the trees within 30 days. Higher stocking rates would be better, but will require moving the fence more often. Trees and other perennial plants have high energy reserves in their root systems and repeated defoliation over a few years is required to control them. Cedar trees however, will not re-sprout and thus, if the goats remove most of the needles and/or bark, the tree will eventually die. Other issues that need to be addressed before getting goats may include predator control (e.g. coyotes) and perhaps learning how to raise goats for meat production. A good place to start is at the ATTRA - National Sustainable Agriculture Information Service web site. The page “Goats: Sustainable Production Overview, Livestock Production Guide” http://www.attra.org/attra-pub/goatoverview.html has information on numerous topics relating to meat goat production.

Many ranchers in other parts of the US have run cattle and goats together for decades. They view goats both as a profitable part of their business and as a very important part of their grazing land management program.

Use of prescribed fire for red cedar control - This method is inexpensive and very effective against smaller trees. Its effectiveness declines as tree size increases, however there were cases of successful burning of tall trees. Adequate fine fuel (usually, last year's dead grass) is necessary for satisfactory results. Safety also is a concern since many managers lack experience with fire and the equipment required to conduct fires.

The controlled use of fire is a large subject in itself. It is beyond the scope of this publication to provide detailed instruction on conducting prescribed fires. Two other Nebraska Extension publications provide information on the use of fire in general and on how to safely conduct fires. They are NebGuide G88-894, “Grassland Management with Prescribed Burning”, and Extension Circular 90-121, “Conducting a Prescribed Burn”. A fire plan should be prepared and a prescribed-burning permit obtained from the local fire jurisdiction, as required by state law. Specialized fire equipment can be purchased. Two sources are the Ben Meadows Company, 3589 Broad St. , Chamblee , GA 30341 ; and Forestry Suppliers, Inc, Box 8397 , Jackson , MS 39284-8397.

Chemical control of eastern red cedar - Herbicides can also be considered for control of this tree species, however, they should be viewed as just another tool in the integrated management program. Depending on the application method and chemical type, the use of herbicides can be time consuming and expensive, especially when used on denser tree infestations or large tracts of land. Effectiveness also is variable depending on the tree size and label directions and/or restrictions. Therefore, always read and follow herbicide label directions. Herbicide information on control of troublesome plant species, including eastern cedar, is update annually in the Guide for Weed Management in Nebraska (EC-130) In general, herbicides for eastern red cedar control can be used for broadcast application or individual-tree spraying.

Broadcast treatments: Broadcast application is the most common method of applying herbicides in agricultural settings. The key message for the efficacy of broadcast treatments in eastern red cedar control is: “the shorter the tree the better control”.

Since tree height was the most important factor influencing the level of chemical control (tree injury) with broadcast treatments, the herbicide efficacy data from Nebraska study was categorized by tree height (Table 1). Recommended herbicides for trees that are up to two feet tall include: Surmount, Grazon P&D and Tordon (Table 1). However, the same herbicides will not provide satisfactory control of trees taller than 2 ft, indicating the importance of tree height. Surmount at the rate of 5 pts/acre can also cause short-term grass injury in the form of leaf yellowing and top growth burning. The cost of Grazon P+D and Tordon 22 K for broadcast applications can range from $21-$26 per acre. Since Surmount is not marketed product yet, the cost is not known.

Individual-tree treatments: Individual-tree treatments can be applied directly to the tree foliage or to the soil around tree base. Soil treatments can minimize the amount of herbicide used and the exposure to non-target species. However, soil treatments may not be effective unless applied before rainfall, preferably in spring or fall. Rain water is needed to move the herbicide into the root zone allowing an easier uptake. Recommended herbicides for soil application around the tree base include Tordon 22K at the rate of 1 cc (ml) per every foot of tree height, Velpar-L at 4 cc (ml) and Spike 20P at 1cc (ml) per every inch of tree diameter. Cost of Tordon is about $85 per gallon, Velpar is about $65 per gallon and Spike 20P is about $9 per pound of product.

Individual-tree foliage can be also treated with various herbicides. Based on a study conducted in northeastern Nebraska, recommended herbicides for control of 2-10 feet tall trees include Surmount at 1.5 % volume per volume (v/v), Grazon P+D at 2.0% (v/v) and Tordon 22K at 1.0% v/v (Table 2).

To help you determine volume per volume basis, for example, the 1% v/v equals 1 gal of product per 100 gal of water. For smaller back pack sprayers use an equivalent of 1.3 oz of product per every gallon of water. Apply about 1.5 oz of the herbicide spray solution per every foot of tree height. Walk around the tree and just spray enough solution just to get a glisten (shine) on the canopy surface. Solution dripping off the canopy indicates a rate that is too high, and a likely waste of time and money. As an example, it was calculated that 1 gallon of spray solution could cover 15 individual trees that are 6 feet tall at a pressure of 20 PSI and a single nozzle type XR8002.

Grass injury in the form of temporary yellowing and burning of top growth was evident among all treatments, especially for Tordon 22K. Roundup is not recommended for use in pasture settings due to poor activity on cedar trees and high injury level to the grass. The cost of Grazon P+D and Tordon 22 K can range from $11-$16 per acre.

Practical hint for chemical control: Use of selective herbicide treatments should be based on tree height. Broadcast treatments are effective only on short trees (up to 2-ft tall), while the medium height trees (2 to 10 ft) can be controlled with individual tree treatments. For broadcast treatments use 6-8 pts of Grazon P&D or 4-5 pts of Surmount in 20 gallons of water per acre. To prepare 1 gal of spray solution for individual-tree canopy treatments use 1.3 oz of Tordon, or 2.6 oz of Grazon P&D, or 2 oz of Surmount. For larger spray tanks adjust herbicide rates accordingly.

Take home message - Since there are many different scenarios under which eastern red cedar trees grow, they obviously can not be managed by a single IWM control method; however, if the methods are implemented in a systematic manner, significant advances in eastern red cedar control can be achieved. Obviously you can not use all of the above described techniques at once. We recommend using the best combination of techniques for your needs. There are many ways to start developing an IWM program. The easiest start will be to try a one or two techniques and then add more practices as the time goes on or the field conditions change. The cost of control methods can also vary, so choose the operation that can fit your budget the best.

We recommend using tree height as a determining factor for control options. There are many control options for trees that are up to 2 feet tall, which may include: cutting, pulling, digging, mowing, burning, use of goats and broadcasts herbicide application. Trees that are 2-10 feet tall can be controlled effectively by cutting and individual-tree herbicide treatments of soil or foliage. Trees that are over 10 ft in height are the most effectively and economically controlled by cutting. Therefore, in order to save time and labor expenses the main take-home message is to “control Red Cedar trees while they are small”.

Table 1. Percent eastern red cedar control and grass injury levels at about 100 days after treatment as influenced by the tree height (feet) where herbicide treatments were broadcast applied.

Table 2. Percent of eastern red cedar and grass injury at 100 days after treatments applied to individual trees.

David P. Shelton
Extension Agricultural Engineer

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