Protecting Your Investment in Winter Cereal Planting

Planting winter cereals in Idaho- protecting your investment.
University of Idaho. Pest alert, September 12, 2013.
Dr. Juliet M. Marshall, Cereal Agronomy and Pathology
Dr. Arash Rashed, Entomology, Aberdeen R&E Center

Over the past several years our winter cereal production, in Idaho, has been negatively impacted with various arthropod pests and disease, including Barley Yellow Dwarf Virus (BYDV).
Below, are a few suggestions made to improve the overall health of our winter crops and to reduce the risk of significant yield loss due to disease problems:

Control volunteers and eliminate "green bridges".
Volunteer wheat and barley, as well as wild grasses, can host various pests of small grains, which may later invade your newly emerged winter crop. Break the green bridge by removing volunteers and having at least two weeks where there is no available host material. Corn is also a host for some insects and diseases that will affect cereals. For instance, aphids can transmit BYD virus from corn, which can harbor the virus but not be affected by it. Some evidence suggests that insecticide sprays in corn and in grassy borders would be effective in reducing BYDV incidence.

Small grains and other grasses (including grassy weeds) are known to host various cereal aphids (i.e. bird cherry-oat aphid, corn leaf aphid, and English grain aphid), and in the case of BYDV, the virus itself. Thus, crops like beets and alfalfa are not expected to act as a source of BYDV. If BYD virus was in your barley planted near beets last year, you likely had volunteers and grassy field borders as the source of infection. Fields could also be infected by newly arriving virus-carrying aphids.

Use treated seed.
Insecticidal seed treatments can reduce aphid colonization of the crop, and subsequently, the secondary spread of BYDV. However, you may still get some virus transmission until the aphids ingest lethal levels of insecticides. Insecticides will also reduce the impact of wireworm feeding. Fungicides are also important for reducing soil and seed-borne diseases and early infection of seedling diseases.

Use resistant varieties.
The most effective means to reduce diseases (stripe rust, for example) is to select varieties with resistance. For some diseases, such as BYDV, we don't have wheat varieties with known levels of resistance to recommend at this point.

Planting date.
 Follow recommended planting dates for winter wheat and barley, and avoid early planting to minimize the exposure of emerging plants and young seedlings to virus-carrying aphids and other pests.

Seeding depth.
In our dryland areas, we have had enough rainfall to replenish soil moisture in the seeding zone. With adequate moisture for rapid germination, you should not be planting deep - this year plant shallow - 1 to 1.5 inches will promote rapid emergence, good stand establishment and will help plants to withstand soilborne diseases such as Fusarium dryland crown rot. Deep planting will force the seed to expend more energy getting to the soil surface, weakening the seedling. It will also increase the chances of crusting prior to emergence. Under irrigation, the same practices apply - with adequate moisture, never plant deeper than 1.5 inches.

Seeding rate should be calculated based on seeds per acre, not lbs/A. Seed irrigated crops at 1 to 1.2 million seeds per acre when planting in our recommended planting window, as winter cereals will tiller adequately. Obviously, if you have to seed later following potatoes or sugar beets, there is less time for plant development and you should increase your seeding rate. If you have a very rough seed bed, increasing the seeding rate will also improve uniform plant stands. Under dryland conditions, reduce the seeding rate significantly, to 600,000 seeds/A for winter barley and 700,000 seeds/A for winter wheat.

 Feed the seed.
Use phosphorus to promote good root development. Starter fertilizers go a long way to promoting healthy crops, even when soil tests indicate adequate phosphorus levels. At high soil pH, phosphorus becomes unavailable, so even 10-15 lbs in furrow or below the seed can make considerable differences in root development and plant health.

Feed the plant.
Soil test to determine available nutrients. Fertilize for expected yield. Consider adding 10-20 lbs/A KCl for straw strength and disease reduction. Sulfur is very important for end-use quality, and 20-40 lbs of sulfate per acre is strongly recommended for protein quality of hard red and hard white winter wheat.

Scout for problems.
Monitor crops as they are growing for symptoms of nutrient deficiencies, weed infestations, insect problems, and disease incidence, and treat according to recommendations. The faster your remedy yield-robbing maladies, the greater your yield potential.
As a general rule, agronomic and cultural methods must be practiced, not only to reduce immediate risk, but also to help to achieve a sustainable pest management in the long run.

Arash Rashed, Ph.D.
Assistant Professor, Entomology
Aberdeen R&E Center
1693 S 2700 W
Aberdeen, ID 83210
208-397-4181
arashed@uidaho.edu
Juliet Marshall, Ph.D.
Associate Professor, Cereals Pathology and Agronomy
Idaho Falls R&E Center
1776 Science Drive Suite 205
Idaho Falls, ID 83402
208-529-8376 office
208-390-4859 cell

http://www.extension.uidaho.edu/scseidaho/