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AgAlerts 2003 From Griggs County
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Issue # 8, July 3, 2003
I have been receiving several calls
concerning wheat heads appear to have an brown powdery substance on the heads
where the spikelets should be. This disease is loose smut and it is a
fungal disease that can infect both wheat and barley.
Disease Cycle: Infection occurs only during flowering. Spores
of the fungus that land in a wheat flower germinate there, and the developing
mycelium penetrates the ovary and establishes itself in the embryo. As the
seed matures the mycelium becomes dormant; such infected seed does not differ
outwardly form healthy seed. When an infected seed germinates, the
mycelium also stars growing again and penetrates the growing point of the
host. As the head begins to form it is so thoroughly invaded by the fungus
that a mass of spores develops instead of the normal spikelets. The spores
mature by heading time and are dispersed by wind and rain the disease cycle
starts over again.
Control: Plant resistant cultivars, using smut free seed or by
applying a systemic seed treatment fungicide registered for loose smut
control. Seed treatment is the most common control method. Be sure
to scout fields that will be used for seed in 2004. If smut is a problem,
plan on seed treatments. The embryo test can be used by the State Seed
Department to determine if loose smut is present in barley seed. This test
cannot be used for the loose smuts of oats or wheat or black semi-loose smut of
barley. All current barley varieties are susceptible to loose smut. An embryo
test is recommended for barley seed; if infection is 2% or greater, seed
treatment of barley with carboxin or triadimenol is advised. Consult the 2003
NDSU Fungicide Guide for products registered for smut control.
NDSU plant pathologists are urging growers to
be on the look out for anthracnose of dry beans, Colletotichum
lindemuthianum. At present, this disease has not been a problem in ND and
we do not want that to change.
This is a seed borne disease that prefers wet and cool
conditions for development at any crop stage. Symptoms of anthracnose can
appear on the leaves, petioles, and pods. Leaf symptoms may appear as dark
brown lesions that follow the vein pattern of the leaf. In wet weather,
masses of spores that are pink to orange in color may appear on the
lesions. These spores may spread to other parts of the field, if
cultivation occurs while the leaves are wet.
Control: The first step is to plant certified disease-free
seed. Seed treatments are not effective in eradicating the seedborne
fungus and data concerning foliar fungicides is available for their efficacy on
this disease from NDSU. For pictures and more information click on the
following link: Manitoba
Pest Management, Anthracnose on Dry Beans
Please Contact Our Office For Additional Information
E-mail: john.swenson@ndsu.edu
Go to the 2003 AgAlert Index Page