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ISSUE 1  May 4, 2000

SECTION 18 GRANTED FOR GUSTAFSON LSP AND MERTECT LSP SEED TREATMENT OF LENTIL

   A section 18 was granted for the application of either Gustafson LSP or Novartis’ Mertect LSP to lentil seed for control of seed borne Ascochyta. LSP is to be applied at the rate of 1.7-3.0 fl oz/cwt of seed using a slurry, ready-mix or spray mist treater. This section 18 is for control of seed borne Ascochyta only; it does not provide any postemergent protection of plants grown in or near infected fields. Do not graze livestock on treated areas for four weeks after planting.

 

APRON MAXX RTA REGISTERED FOR SEED TREATMENT OF SOYBEAN

    Apron Maxx RTA was registered this spring for seed treatment of soybean. It is formulated for on-farm treatment, using standard mechanical slurry or mist-type seed treatment equipment which accurately measures and mixes a flowable seed treatment. Containing the fungicides mefenoxam (Apron XL) and fludioxonil (Maxim), Apron Maxx RTA provides good control of soil borne diseases including Pythium, Phytophthora, Rhizoctonia and Fusarium. It also provides suppression of seed
borne Sclerotinia and Phomopsis.

    Since mefenoxam and fludioxonil have very little negative effect on the survival of Rhizobium bacteria or on nodulation, Apron Maxx RTA is one of the safest products to use with an inoculant. Novartis, the registrant of Apron Maxx RTA, has its own proprietary inoculant, Cell Tech 2000, which can be tank mixed with Apron Maxx RTA. The tank mix must be applied to soybean seed using a slurry or mist type treater capable of providing accurate seed treatment rates. The slurry must be applied to the seed within 4 hours. The treated seed must be planted within 24 hours of treatment. The combination of Apron Maxx RTA and Cell Tech 2000 may leave the seed a little moist, which will restrict normal flow of seed in the planter; a drying period of an hour or so will allow the seed to dry sufficiently that seed will flow normally in the planter.

 

PLANTING SUNFLOWER NEAR FIELDS THAT HAD SEVERE HEAD ROT IN 1999

    Questions have been raised about the danger of planting sunflower near fields that had severe head rot in 1999. The most important consideration with sunflower and Sclerotinia is the history of the field in which the crop is being planted. If sunflower is planted into a field that is infested with Sclerotinia, the crop will be infected through the roots, resulting in Sclerotinia wilt. This will occur in almost any weather conditions.

    The danger of head rot from a nearby field will depend on weather at heading. Head rot, like infection of canola and dry beans, depends on wet weather at flowering, which favors germination of the sclerotia (the hard, black bodies), production of the mushroom bodies (apothecia) from the sclerotia and release of spores from the apothecia. Wet weather also is required for spore infection. Generally, heading time for sunflower is in August and September, and this tends to be a drier time of the year than in late June or July when dry beans and canola are flowering.

 

A USEFUL WEB SITE FOR CANOLA

Canola Connection (Canola Council of Canada Web Site):
http://www.canola-council.org.


    This web site contains the entire "Canola Growers Manual" (information on varieties, fertility, production practices, pests and harvest), an "Image Library", links to many other sites ("Sites to Visit") and a section on "Weather and Crop Forecasts". The "Sclerotinia Risk Maps" are found under "Weather and Crop Forecasts". These maps show the risk of Sclerotinia stem rot infection across the prairie provinces of Canada. The maps stop at the border, however, so are most useful to producers who are near the Canadian border.

Art Lamey
Extension Plant Pathologist
alamey@ndsuext.nodak.edu

 

WHEAT LEAF RUST PROGRESS IN SOUTHERN PLAINS

   Wheat leaf rust is severe in central Texas on susceptible cultivars, but severity is light to moderate in commercial fields of more resistant cultivars. Leaf rust was detected several weeks ago in Kansas commercial wheat fields, but levels have not increased much there the past two weeks because dry weather has limited further development. We must be alert to development of this disease in southern plains states, as the levels there are early warnings of rust potential for our crops. Leaf rust moves into the state via southerly winds that are carrying spores from these infected fields.

 

WHEAT LEAF RUST RACE DETECTION IN ND, 1999

    The severity of wheat leaf rust on many cultivars in ND in 1999 resulted in collection of 150 leaf samples for race identification. Some of these leaves were collected by personnel from the USDA Cereal Disease Lab in St. Paul, MN, others were collected by NDSU and USDA personnel in ND. All samples were processed for determination of leaf rust races by the USDA Cereal Disease Lab in St. Paul, MN.

    T races were found on 64.4% of the 150 leaf samples, and six different T races were distinguished. In 1998, 78 ND wheat samples were analyzed for leaf rust race identification, and 44.9% had a T race. Thus, the percent of T races recovered has increased, indicating a substantial shift from M races being prevalent to T races of rust being prevalent in ND. Most leaf samples were not identified as to cultivar source, but for those that were identified, 14 different cultivars were infected by a T race.

 

BARLEY YELLOW DWARF VIRUS (BYDV)

   Barley yellow dwarf virus (BYDV) symptoms are widespread and clear cut in much of Texas. In Kansas, the aphid vectors of BYDV are commonly found, including greenbugs, English grain aphid, and Bird Cherry-Oat aphid. BYDV is the predominate disease observed in Kansas wheat fields now, with incidences of infected plants sometimes reaching 90-95% in a single field. The occurrence of BYDV in these southern plains states is important to ND producers, because the aphids that transmit this virus are carried into our state via southerly winds from these affected areas.

 

SMALL GRAIN DISEASE WEB SITES

   Some small grain disease web sites that I use frequently during the growing season for learning about disease progress are:

Cereal rusts: http://www.crl.umn.edu/crb/crbupd.html

Wheat diseases and insects in Kansas:
http://www.oznet.ksu.edu/dp_path-ext/newsletters/Indexpageforallalerts.htm
http://www.ink.org/public/kda/phealth/phprot/pltpro.html

ND Disease forecasting:
http://www.ag.ndsu.nodak.edu/cropdisease/

NDSU Plant Pathology Department
http://www.ndsu.nodak.edu/plantpath/

Fusarium head blight (scab)
http://www.scabusa.org/
http://www.ndsu.nodak.edu/instruct/stack/FHB/FHB.html

Marcia McMullen
Extension Plant Pathologist/IPMCoordinator
mmcmulle@ndsuext.nodak.edu


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