Fargo, North Dakota
March 16, 2006
Due to regional disease problems
in some pulse crops (dry peas, lentils and chickpeas) last year,
it may be a good idea to have seed tested for the presence of
Ascochyta diseases before planting. Seed can be tested locally
at the North Dakota State Seed Department and
North Dakota State
University plant diagnostic lab.
Although all three crops are affected by Ascochyta diseases,
different fungal pathogens cause the disease on each crop,
according to Carl Bradley, NDSU Extension Service plant
pathologist.
On lentils, Ascochyta blight is caused by a fungal pathogen
specific to lentils. Ascochyta blight can be transmitted readily
from the seed to the seedling at a fairly high rate.
"For this reason, growers should have their lentil seed treated
with either LSP or Mertect if Ascochyta is found in the seed,"
Bradley says.
A recently obtained section 18 emergency exemption allows for
the treatment of lentils with LSP or Mertect. Seed lots that
have Ascochyta infections of more than 2 percent to 3 percent
probably should not be used for seed.
On chickpeas, Ascochyta blight is caused by a fungal pathogen
specific to chickpeas. Similar to Ascochyta on lentils, chickpea
Ascochyta blight can be transmitted readily from the seed to the
seedling at a fairly high rate.
"Because Ascochyta blight can be extremely damaging to chickpea,
it is encouraged that seed lots with 0 percent infection be
used," Bradley says. "However, if disease-free lots are not
available, then lots with less than 0.3 percent infection could
be used if they are treated with LSP or Mertect. LSP and Mertect
are available for use on chickpea seed through a special local
needs section 24(c) label for North Dakota."
On dry peas, Ascochyta diseases can be caused by a complex of
three different fungal pathogens that are specific to dry peas.
"Because the rate of disease transmission from dry pea seed to
the seedling is so low, seed lots with up to 4 percent to 5
percent infection should be OK to plant," Bradley says. "No
fungicide seed treatments are available for dry peas that
protect against seed-borne Ascochyta diseases in North Dakota."
For more information on plant diseases in North Dakota and seed
testing, go to the following Web sites:
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