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AgAlerts 2003 From Griggs County
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Issue # 5, June 12, 2003
The NDSU IPM scouts have been finding cereal
aphids in the eastern part of the state this past week. One aphid of
particular concern has been the numbers of Bird Cherry-Oat Aphid (BCOA).
This aphid can transmit Barley Yellow Dwarf virus (BYDV). There is no
control for BYDV except trying to control the vector. But this is not a
guaranteed solution.
At this point, infestation levels have been from 25% to as
high as 50% of the plant stems infested. Yield losses occur when 85%
infestation levels are achieved. So at this time, monitor wheat and barley
fields for aphid presence. For more information and identification
information, consult the following publication.
Aphid
Management in Small Grains, Corn and Sorghum E-493.
The Griggs County Weed Board is going to be
holding collection days for leafy flea spurge beetles when emergence numbers
warrant collection. Keep watching this web site for collection dates,
times and locations. We will have sweep nets available along with bags for
transportation. Coolers equipped with blue ice containers are
preferred. Ice bags are not recommended due to the possibility of the bag
leaking and drowning the insects. One other option is the use of frozen
water bottles with some type of barrier between the insects and the frozen
containers of the bags will not get wet.
The weed board will try and make an effort to arrange for
collection of insects for those that cannot be present at the site. There
will be a slight fee for this service. If you are interested in this,
contact the Extension office for times and dates that this service will be
available. We will be checking out sites this next week and a report will
be posted on this web site.
Cool wet conditions this spring have cause
ash trees to be infected with anthracnose, which is caused by a fungus called
Gnomoniella fraxini. Besides premature leaf drop, symptoms include
deformed and discolored leaves. Leaves may show brown to black lesions,
often associated with leaf veins; and the leaves may curl along the main vein.
While premature leaf drop is dramatic, it is not usually detrimental to the tree
since a flush of new growth will follow. If defoliation occurs over a
number of years, this could have an affect and cause early decline.
The best management for this disease is to rake up and
destroy all the fallen leaves. This will reduce the amount of pathogen
available to cause new infection. Fertilizing with high ratios of nitrogen
to promote growth will provide for optimal refoliation.
How long can a crop survive in flooded
conditions is environmentally dependant. Under cool cloudy conditions, soybeans:
about 3 days, drybeans: about 1 day, and corn: 2 to 3 days. Under sunny and warm
conditions, soybeans: 1.5 days, drybeans: ½ day, and corn 1 to 1.5 days. As
temperature and sunny conditions increase, the amount of time decreases.
Soybeans become nitrogen deficient and also susceptible to
iron chlorosis under flooded conditions. Phytophthora root rot in susceptible
varieties is frequently associated with flooding damage. Flooding causes
anarobic conditions (lack of oxygen) which will cause root damage. As waters
subside, plants may start to appear normal but will be stunted and yield losses
may occur.
What volume of water is associated with a one
inch rainfall event. Doing the math, a one inch rain will yield the
following:
27,150 gallons water per acre
4,344,000 gallons per quarter
17,376,000 gallons per section
625,536,000 gallons per township
Please Contact Our Office For Additional Information
E-mail: john.swenson@ndsu.edu
Go to the 2003 AgAlert Index Page