Growing degree day and evapotranspiration data updated daily in CropWatch

Soybean aphid

Two aphids were found in a field near Peru in Nemaha County and two were found in a field south of Union in Otoe County. Three of the aphids were winged, indicating they likely had just arrived. While numbers may be low at this time and aphids have not been found in the rest of the state, farmers should consider this an early warning signal to gear up their scouting efforts for this insect.

The aphid is light green to pale yellow, less than 1/16-inch long, and has two black-tipped cornicles (cornicles look like tailpipes) on the rear of the abdomen. It has piercing-sucking mouthparts and typically feeds on new tissue near the top of soybean plants or on the undersides of mature leaves. Later in the season aphids can be found on all parts of the plant. It is the only aphid in North America that forms colonies on soybean.

Soybean aphids reproduce more quickly in cool environments -- optimum conditions are 72°-77°F with a relative humidity below 78%. Development slows when temperatures exceed 81°F. High temperatures may have been what kept the aphid pop-ulations at low levels last year in Nebraska.

Soybean aphids have been found to be economically damaging when at high numbers during the late vegetative and early reproductive soybean stages. From now through June, farmers should scout their fields to see if aphids are present.

In next week's CropWatch I will present more information on soy-bean aphid biology and management.

Fourth instar nymphal stage of the differential grasshopper, one of the four species known to cause serious damage to Nebraska crops. For more photos to aid in identifying grasshopper species in crops, see a special Grasshopper Photo page.

Just after egg hatch, when grasshoppers are small, they will be difficult to see and underestimating the true hopper density is common. The best method for determining grasshopper density in field borders or hatching areas is to estimate the number of grasshoppers per square foot in several places. Randomly select a spot several feet away and visualize a one-square-foot area within that defined area. When first learning this method, measure off a one square-foot area to "calibrate" your ability to visualize the counting area.

Walk toward this spot and while watching this square-foot area, count the number of grasshoppers in or jumping out of the area. Repeat this procedure 18 times and divide the total number of grasshoppers by two. This will give you the number of grasshoppers per square yard (9 square feet). Counting sites should be 50-75 feet apart and randomly chosen. Populations of 20 or more young grasshoppers per square yard are considered a moderate infestation, but such numbers should probably be treated to prevent damage.

When scouting look first in untilled areas where grasshoppers would have laid their eggs last fall. These would include roadside ditches, disturbed weedy areas adjacent to fields and property lines, pastures and alfalfa fields. Determine the lifestage, species and number of grasshoppers. Since not all species of grasshoppers are likely to cause significant damage, it's important to try and identify the specific species to avoid unnecessary insecticide applications.

When hoppers are found in "significant" numbers, control should be considered. To prevent grasshoppers from invading fields and acreages, consider treating the hatching and staging areas while the hoppers are small and not eating much. For non-crop borders, carbaryl (Sevin), dimethoate (Cygon), esfenvalerate (Asana), malathion and diflubenzuron (Dimilin) may be used effectively. In pastures, farmers can use carbaryl (Sevin), malathion and diflubenzuron (Dimilin).

In our state insect problems in stored grain originate from infested grain trapped in harvesting equipment, in the bin itself, or nearby, but not in the field. Proper equipment and bin preparation can help ensure that grain quality is maintained in storage.

Cleaning bins, equipment

Grain harvesting and handling equipment such as combines and augers must be thoroughly cleaned so that insect-damaged or moldy grain is not dumped into the first new crop grain passing through the equipment. Carefully inspect and remove all traces of old grain from combines, truck beds, grain carts, augers, and any other equipment used for harvesting, transporting, and handling grain. Clean grain bins thoroughly, disposing of spilled, cracked and broken grain and grain flour, along with the insects feeding on this material. A simple broom, bucket, and a vacuum cleaner are essential pieces of equipment in cleaning grain bins.

Around the bins, be sure to remove old equipment, junk and clutter to reduce attractiveness to insects and rodents. Make sure that the bin is insect- and rodent-proofed by plugging holes, sealing bins, caulking and making general repairs. Grain spilled near the bin attracts insects and draws mice and rats. Clean up and dispose of any spilled grain a few weeks before harvest. If rats have tunneled under foundations, use baits or traps to reduce or eliminate them.

Tall weeds can harbor insects and provide cover for rodents. Mow around the bin site to remove tall grass and weeds to reduce the potential for insect and rodent infestation. If necessary, re-grade the site so that water readily drains away from bin foundations. In the midst of harvest you won't want to wait for wet soil to dry out.

Make certain that travel lanes have enough rock or gravel to bear the weight of heavy trucks and grain carts. Using geotextile fabric will increase the effectiveness of gravel and crushed rock for the travel lanes and around the bin perimeters. The fabric is inexpensive and can extend the life of gravel by up to 10 times. Landscaping should be maintained well away from grain storage facilities. Leave a 4-foot wide strip of bare gravel around the perimeter of storage bins.

Treating empty bins

Once empty bins have been thoroughly cleaned, a residual treatment may be applied to bin surfaces to protect incoming grain from insect infestation. Follow label instructions carefully. Note that the following recommendations are for bins that will store wheat. (A later issue of CropWatch will address recommendations for preparing bins for corn and soybean storage.) The following materials can be applied as residual sprays to empty wheat bin surfaces: silicon dioxide, silica gel plus pyrethrins, pyrethrins, malathion and diatomaceous earth. Note that pyrethrins would provide a relatively short residual and that malathion is not effective for some stored grain insects due to resistance. For bins with false floors, which are inaccessible for cleaning, chloropicrin, a bin "clean-out" fumigant, is legal to use prior to binning the wheat. Other fumigants that could be used on empty bins are magnesium phosphide and methyl bromide. Caution! Fumigants are dangerous, restricted use pesticides and may require gas monitoring devices and respirator protection for the applicator. It is highly recommended that fumigation be done by a commercial pesticide applicator who has been trained and EPA/NDA-certified in safe fumigant handling and application techniques. Refer to current labels for specific details and instructions.

Grain storage and temperature

After cleaning the bins and equipment, the next step is to ensure the quality of the grain going into storage. It must be clean, sound and dry and it's essential that it be relatively free of fines (cracked grain), trash and foreign material. Never put new crop grain on top of old grain in the bin.

Stored grain insects cannot live on extremely dry grain (less than 10% moisture), however it is impractical to reduce grain moisture much below minimum moisture levels necessary for long-term storage. The safe storage moisture level for wheat is about 13%. Insect activity and reproduction are favored by high grain moisture, especially when condensation and molds occur and fermentation raises the grain temperature. Spoilage and internal heating allow insects to remain active -- even in winter.

Proper bin aeration can help manage grain temperature. Since insects are "cold-blooded", they are less active at lower temperatures. Maintaining "cool" grain can be particularly important in reducing insect reproduction. Condensation of moisture in the grain mass is prevented by slow cooling and gradual reduction of the gradient between the grain mass temperature and the outside (ambient) temperature. In summer, keeping the grain cool is a challenge, so timely aeration is important.

Typical harvest temperatures may produce a grain mass that starts off at 95^oF or higher. In a 1994 study, Kansas entomologists found that proper aeration and cooling after harvest could eliminate the need for grain protectants in many cases.

Treating stored wheat

Diatomaceous earth or natural pyrethrins can be applied directly to wheat as it goes into the bin. Once wheat is in storage, surface infestations of Indianmeal moth may be prevented with Bacillus thuringiensis kurstaki (Dipel, etc.). If found to be seriously infested with insects later in the summer, the grain mass can be fumigated. Fumigants approved for use on wheat include: magnesium phosphide and aluminum phosphide. Other stored wheat treatments include: diatomaceous earth, silicon dioxide and pyrethrins.

"There have been no cases of Karnal bunt ever reported in Nebraska," Carlson said. "But I feel it is important to implement this precautionary measure to protect our Nebraska producers."

Carlson issued the amended quarantine in support of the federal Karnal bunt quarantine. The United States Department of Agriculture, Animal and Plant Health Inspection Service, Plant Protection and Quarantine (USDA/APHIS/PPQ) has advised the NDA that the wheat disease had been detected in Maricopa, Pinal, and La Paz counties in Arizona; Throckmorton, Young, McCulloch, San Saba, Archer, Baylor and Knox counties in Texas; and Imperial and Riverside counties in California. The amendment adds additional quarantined counties. The USDA requires that every piece of farm equipment used in a Karnal bunt regulated area be cleaned before it is moved, and equipment operators are given a certificate to confirm the cleaning has taken place. NDA officials will be checking custom harvesters at various locations to make sure any equipment used in quarantined areas has been issued special USDA certification.

Carlson recommends producers talk to their harvest crews.

"Growers need to be very careful about the equipment they allow into their fields so the disease isn't accidentally spread to Nebraska. If the harvest crew has been in an area known to have Karnal bunt, find out if the equipment has been properly cleaned and if the operator has a certificate issued by the USDA," he said.

Karnal bunt is caused by the fungus, Tilletia indica, and is spread by spores primarily through movement of infected or contaminated seed. While it does not threaten human health, flour made from blunted kernels is discolored and has a harmless but unpleasant odor and taste. Perhaps, the most harmful impact of the disease, Carlson said, is the economic loss it can cause. Numerous countries restrict the import of U.S. wheat grown where the disease has been found. In addition, NDA officials will collect statewide wheat samples that will be part of a nationwide survey for the disease.

Nebraska Department of Agriculture Press Release

With farmers being unable to enter wet fields after recent rains, weeds have taken advantage of the situation in some Nebraska fields. Photo by Brett Hampton

Late season weed control in corn greater than 12 inches

Accent - up to 36-inch corn. If greater than 20 inches, use drop nozzles.

Aim - up to 8-leaf corn (approximately 30 inches)

Callisto - up to 8-leaf corn (approximately 30 inches)

Clarity - up to 36-inch corn. Use caution with nearby sensitive broadleaf crops. Use directed application if possible.

Distinct - up to 24-inch corn. Use at 4 oz /A rate

Exceed - up to 30-inch corn. Greater than 20 inches, use drop nozzles.

Glyphosate - up to 30-inch corn. If greater than 24 inches use drop nozzles. Requires Roundup Ready corn

Liberty - up to 36-inch corn. Requires Liberty Link corn

Lightning - 45 days before harvest - Requires Imi/Clearfield corn

Northstar - up to 36-inch corn. Greater than 20 inches, use drop nozzles.

Option - up to 36-inch corn. If greater than 16 inches, use drop nozzles.

Roundup WeatherMax - up to 30 inches corn. If greater than 24 inches, use drop nozzles. Requires Roundup Ready corn.

2,4-D amine - up to tasseling. Use drop nozzles for corn more than 8 inches. Use caution with nearby sensitive broadleaf crops.

Yukon - up to 36-inch corn. Weeds 1-6 inches tall.

"Drought conditions in the area seem to have mitigated to some degree this spring, but I think most would agree that it's way too early to say the drought in southwest and south central Nebraska is over," said tour co-organizer Michael Jess, associate director of UNL's Conservation and Survey Division and acting director of the UNL Water Center.

"The tour will focus on local responses to settlement of the Kansas vs. Nebraska lawsuit and how producers in the Republican River watershed are coping with the ongoing drought," he said.

The tour leaves Kearney at 8 a.m., Tuesday, July 22. Stops that day include Dancing Leaf Lodge near Wellfleet and at Imperial for discussions with local natural resources district officials on water well permit moratoriums, metering compliance and exchange of groundwater among local irrigators. Near Benkelman, tour participants will look at the south fork of the Republican River where it flows from Kansas into Nebraska. Overnight is at McCook, where the evening meal will be served in the city park next to the George Norris house.

On Wednesday, July 23, the tour stops at Harry Strunk Reservoir to look at outcroppings of the Ogallala formation. Later, officials of the Frenchman-Cambridge Irrigation District will address drought and lawsuit settlement issues in their district before the tour proceeds to lunch in Alma and discussions with Lower Republican NRD officials. The group will get a close look at Harlan County Reservoir as well, including a discussion of geological exposures and faulting visible along the reservoir's south shore. Overnight is at Hastings.

The first stop on the final day of the tour, Thursday, July 24, will be at the Guide Rock Diversion Dam, where the Courtland Canal diverts Republican River water to neighboring Kansas. There, Nebraska Bostwick Irrigation District officials will explain operational obligations and deliveries of water to the Kansas Bostwick Irrigation District. The tour then proceeds to Red Cloud for lunch in the historic hometown of author Willa Cather. Following lunch at the Red Cloud Community Building, tour participants will travel to the Kahrs Farms near Bloomington. There, UNL hydrogeologist Jim Goeke of North Platte and Chris Miller of Miller and Associates of McCook will explain investigations done for the Nebraska Department of Natural Resources and for the Nebraska Attorney General's office.

"The objective of those studies was to learn the extent of surface water/groundwater interaction within a portion of the Republican River valley," Jess said.

The tour returns to Kearney late afternoon. Cost is $375 single occupancy or $325 double occupancy. Registration includes all food, motel, and motor coach expenses. Registration is through the Kearney Area Chamber of Commerce at (800)652-9435. Registration deadline is July 1. Participation is limited to the first 90 registrants.

Tour co-sponsors are Central Nebraska Public Power and Irrigation District, Four States Irrigation Council, Gateway Farm Show, Kearney Area Chamber of Commerce, Nebraska Association of Resources Districts, Nebraska Public Power District, The Groundwater Foundation, U.S. Geological Survey -- Nebraska District and UNL's Water Center and School of Natural Resources.

Steven Ress
Communications Coordinator
UNL Water Center

"These funds will assist Nebraska in better identifying and responding to drought conditions," said Roger Patterson, Director of the Nebraska Department of Natural Resources. "They will be especially helpful in the Republican Basin, an area that has experienced severe drought conditions and is implementing new water management activities in response to the recent settlement of the lawsuit with Kansas. Flow meters to monitor groundwater are an important piece of Nebraska's management efforts and we appreciate Reclamation's assistance in moving forward."

The flow meter cost share funds are expected to be distributed to landowners through the Nebraska Soil and Water Conservation Fund administered by the Nebraska Department of Natural Resources. Mark Svoboda, Climatologist with the National Drought Mitigation Center at the University of Nebraska noted the importance of the funding for expanding the state's automated soil moisture monitoring network.

Svoboda said, "A near real-time soil moisture monitoring network provides for early detection of agricultural drought and provides the ground-truth data to determine crop-specific soil water needs. This expansion will provide more uniform coverage across Nebraska".

The funds will be used to update 25 Nebraska Automated Weather Data Network sites to include soil moisture measurements and to add 10 new Automated Weather Data Network sites. Through the Reclamation States Emergency Drought Relief Act of 1991 the Department of the Interior is authorized to provide emergency response and planning assistance to minimize and mitigate losses and damages resulting from drought conditions.

Saltcedar moves from an ornamental to a pest

It is a perennial deciduous or evergreen shrub or small tree from the tamarisk family (Tamaricaceae) that reproduces both by seeds and perennial structures such as taproot and stem. Root system is extensive with primary taproot easily growing at least 15 ft deep. In search for moisture the taproot can grow downwards as deep as 150 feet. Once the water table is reached, secondary root branching becomes profuse.

The plants (trees) can grow as individual trees or in sparse groups. The woody stem is erect, up to 20 feet tall, and the bark is brown or reddish-brown with highly branched saplinks. Leaves are small, scale-like (as in many cedar trees) with many divisions on slender highly branched green stems. In Nebraska, it can flower from June to August, with small pink flowers positioned on the top of the main woody stem and branches (saplinks) in the finger-like clusters. The flowers produce numerous small tufted seeds that can be carried long distances by wind and water. The seeds, however, have a short period of viability and must contact suitable moisture within a few weeks of dispersal to grow.

Saltcedar is sold as an ornamental plant species, but has escaped and became naturalized along streams, canals and reservoirs in the western United States. In addition, in early 1900 saltcedar was purposely planted along stream banks for soil erosion control.

Unfortunately saltcedar is actually detrimental to the natural habitat. The high evapo-transpiration rate of saltcedar can lower the water table in streams and canals. The salt excreted from the leaves to the soil surface under the plant inhibits germination and growth of competing species. Thus the name “saltcedar” is derived from the salty residue that collects on the small scale-like leaves that resemble cedar foliage. As a result, many wildlife species are negatively effected by habitat changes and native species displacement due to saltcedar.

In addition, the sticky salty substance exuded by the leaves can damage bird plumage. With loss of habitat most wildlife species move to more diverse native plant communities. Because of its detrimental effect on wildlife habitat and land saltcedar is a concern to many private and government land managers.

Saltcedar management

The guidelines for control include:

1. Treat young or regrown plants under 6 feet tall because they are more easily sprayed and controlled than taller trees.
2. Treat areas previously root plowed, mowed or areas where saltcedar appears to be newly invading.
3. Treat area with tree densities fewer than 150 plants per acre.
4. Spray foliage to wet (no dripping) especially terminal ends, and allow two full growing seasons before follow-up management.
5. Time herbicide application toward the later part of the season, but not too late. September and August treatments are much better than May, June or October.
6. Broadcast treatments can be applied via airplane, helicopter or high-clearance sprayers with a water volume of a least 15 gallons per acre for better penetration into the dense canopy. Arial application can be effective using a global positioning spray system matched with the survey maps, allowing the pilot to locate saltcedar sites and exclude sensitive areas such as cottonwood groves and other vegetation. For broadcast treatments Arsenal (imazapyr) is recommended at the rate of 3 pints per acre.
7. Individual trees can be also controlled with Arsenal at 1% volume/volume (v/v). Arsenal is absorbed through foliage and roots and is translocated throughout the plants. Complete kill of plants may not occur within a month or two. In addition, a mix of Roundup (0.5% v/v) and Arsenal (0.5% v/v) is also very effective. Roundup is added to the mix to reduce the cost of the treatment since Roundup (or any generic glyphosate) can be as much as four to five times cheaper that Arsenal alone.
8. Do not treat irrigation ditches and water for domestic use. Do not use near desirable trees and near homesteads. Clean equipment with water following spraying.

Weathering tends to lower the yield and nutrients available from hay by about 1% for each month of exposed storage. High value, high quality hay that will be sold or fed to high value animals should be stored under cover. A hay shed, a partially used machine shed, or any other shelter with a roof will be better than exposing your hay. The next best protection may be tarps, especially heavy-duty ones that can be tied down without tearing in the wind. Plastic also works, but it takes special care to fasten down.

? If uncovered storage is your only option, place bales and stacks on an elevated site with good drainage so moisture doesn't soak up from the bottom. Also, don't stack round bales or line them up with the twine sides touching -- rain will collect where they touch and soak into the bale. And allow space for air to circulate and dry hay after rain.

Starane, which is manufactured by Dow AgroSciences, may be applied following all label directions, restrictions and precautions on the Environmental Protection Agency registered product label, as well as restrictions within the release notice.

Other restrictions include:

Do not make more than two applications or apply more than 1 pint per acre per crop season.

Pre-harvest interval: Do not allow livestock to graze or harvest forage within 40 days of application. Do not apply within 70 days of harvesting grain or stover.

Retailers are required to obtain a permit to sell Starane. Applicators will only be able to purchase sorghum-labeled Starane from permitted dealers. Permits are available from NDA by calling (402) 471-2394.