May 5, 2005 Volume 4 Number 3
1. View from the Field
2. Alfalfa Snout Beetles on the March…
3. When Do Weeds Wake-up in the Spring?
4. Seed Decay and Seedling Diseases of Corn
5. Alfalfa Crown Rot
6. Stagonospora Nodorum Blotch-Small Grains
7. Growing Degree Days in NYS
8. Why did the Dandelions Get Into the Alfalfa Field
9. Clipboard Checklist
10. Contact Information
from the field
Wise, NYS IPM
Hello Field Croppers:
Agriculture (TAg) is a program most of you are familiar with.
This year the LFC IPM team is again working with local CCE personnel
to implement TAg programs across NY. New this year, thanks to
a grant from the NE Soybean Board, we will conduct the first soybean
TAg program in NYS. This new effort will be launched in Oneida,
Orleans, and Cayuga Counties. Local leadership for these county-based
TAg teams will be provided by Jeff Miller, Mike Stanyard and Shawn
Traditional TAg teams (Corn and Alfalfa) will be offered in Lewis
County (Jennifer Beckman), Franklin County (Mathew Copper) and
in Essex County (Anita Deming).
For specific information and TAg resources view the following
webpage: NYS IPM Tactical Agriculture
Snout Beetles on the March
Waldron, NYS IPM
time for the annual alfalfa snout beetle fun run. Warmer spring
temperatures signal alfalfa snout beetle (ASB) adults to begin
their emergence from the fields where they have been feeding as
larvae on alfalfa roots for the past two years. In addition to
alfalfa, other host plants for ASB include: red clover, dock,
wild carrot, quackgrass, and white clover. Nonhosts, i.e. good
crops to have in rotation to minimize ASB losses include: corn,
wheat, oats, soybeans, potatoes, and birdsfoot trefoil.
The annual ASB emergence occurs about the time the shadbush (Amelanchier
sp., aka Juneberry, Serviceberry) blooms. When adults emerge they
tend to migrate in mass numbers often in a northeast or northwest
direction searching for greener alfalfa fields. Once in a suitable
location they feed on new alfalfa shoots and lay eggs that hatch
into the voracious root feeding larvae. Under the right conditions
ASB migrations can be quite impressive with thousands of beetles
seen marching along roadsides from point A to point B. On cooler
days, however, the marches go on but are more sporadic, with less
numbers of beetles at any one time. Such was the case at a location
in Jefferson county last Friday. A slow but steady stream of beetle
Alfalfa snout beetles (ASB) are root-feeding weevils found only
in northern New York State along Lake Ontario and the St. Lawrence
(Clinton to Cayuga), southern Ontario's Wolfe Island and Grenville
and Leeds counties, and in central Europe.
ASB's are mottled gray, humpbacked, 1/2 inch long, do not fly,
and are all females.
larger than alfalfa weevil, alfalfa snout beetles can totally
destroy an alfalfa field in as little as one year. Larvae are
legless, white, 1/2 inch long, and can be found feeding on alfalfa
roots within a foot of the soil surface in mid to late summer.
Larvae feed on side roots, and girdle the main taproot causing
death to the plant. In early fall the larvae move deeper in the
soil where they spend the winter. The following spring the larvae
move 10-12 inches from the surface, pupate by mid-summer and become
inactive adults, which remain in the soil until the following
spring. ASB damage in the spring looks similar to winter killed
alfalfa with plants failing to "green up".
Insecticides are not recommended to control ASB,
however, two possible avenues of management are currently being
researched to control this pest in the future: resistant alfalfa
varieties (Don Viands and Cornell's Plant Breeding Forage Group)
and biological control using entomopathogenic nematodes (Elson
Shields and Graduate Students in Cornell's Entomology Department).
do weeds wake up in the spring?
Wise, NYS IPM
is a good idea to know when certain weeds wakeup in the spring!
Knowing when weed species germinate or break dormancy helps to
select and time management programs that are the most effective.
Weed emergence can be anticipated by considering their response
to growing degree-day accumulation (48F Base Temp.) The following
chart lists some of common weed species and the accumulated GDD's
at which their first flush (i.e. 10%) can be expected to emerge.
There are, of course, other factors that affect weed emergence
such as cloud cover, soil type, soil moisture, crop residue, and
0(Emergence occurs in fall or early spring)
Winter annuals normally complete emergence prior to planting of
Examples: horsetails (mares tail), white cockle, field penny cress,
1(Emergence begins several weeks prior to corn planting, GDD
Examples: giant ragweed, lambsquarters, Penn. Smartweed, common
2(Emergence begins soon, before or at corn planting, GDD 150-300)
Examples: common ragweed, green foxtail, velvetleaf
3(Emergence begins at the end of corn planting season, GDD
Examples: yellow foxtail, black nightshade, common cocklebur,
wild proso millet
4(Emergence begins after corn emergence, GDD 350 >)
Examples: large crabgrass, fall panicum, waterhemp, morning glory
Iowa State University Extension Publication, IPM 64
Decay and Seedling Diseases of Corn
Stavisky, NYS IPM & Ken Wise, NYS IPM
planting is starting, so disease pests that affect emerging seedlings
are not far behind. Early season corn seed and seedling diseases
can reduce plant populations, and corn does not compensate for
gaps in the stand like other crops are able to. Stunting of early
plant growth resulting from non-lethal seedling diseases can lead
to slower maturity and a decrease in overall plant size.
Seed decay is caused by a number of soil-inhabiting fungi
such as Pythium, Fusarium, Diplodia, Rhizoctonia and Penicillium.
These fungi can infect seed before it germinates, causing mortality.
Seeds infected with decay fungi are discolored and soft. Many
times fungal material may grow on the seed. If you are digging
around in the soil to investigate those gaps in the row, a seed
that has rotted may be completely decomposed and therefore cannot
be found. This can make tracking down the culprit a little difficult!
Sometimes the seed may germinate and grow but will die
as the plant emerges from the soil. Seeding blights are caused
by many of the same fungi that cause seed decay. Seedling blight
symptoms include discolored seedling coleoptiles and roots. Seedlings
may have a wet, rotted appearance before they reach the soil surface.
Above ground symptoms of blight may include seedlings that turn
yellow, wilt and die.
that contribute to both seed decay and seedling blights may include
cold, wet soils. These unfavorable conditions can lead to slow
emergence and slow growth of seedlings. Plant or seed injury from
fertilizer burn, incorrect herbicide application, or soil crusting
can add to plant stress at the vulnerable seedling stage. Fortunately,
planting high quality corn seed is common practice, and fungicide
seed treatments are a normal part of the spring routine for many
producers. These practices prevent many outbreaks of seed decay
and seedling blight.
For more information on early season disease management see: our
brochure on Field Corn Diseases.
Wise, NYS IPM
walking alfalfa fields at SUNY Cobleskill this week I discovered
many plants that had frost heaved out of the ground. I cut open
the tap root and most of the plants showed signs of rot in the
crown. Crown rot normally occurs in older fields where there has
been a history of stress, heavy traffic or grazing, poor drainage,
fertility and pH problems, previous insect damage, etc. Plants
exhibiting crown rot appear stunted and have few stems. Crown
rot progresses slowly in the crown and taproot area of the plant.
In many situations, crown rot cannot be attributed to a single
pathogen. Several fungi (Fusarium spp., Phoma, Pythium, Rhizoctonia)
as well as some bacteria, have been implicated in the disease.
Often, a complex consisting of several of the pathogens attacks
the plant. The way to tell if a plant has the disease is to dig
up (not pull up) a plant showing symptoms. Then use a knife to
split open the crowns and roots. Healthy tissue should be white,
moist, and firm. Rotted tissue usually has a black or brownish-
red color, but the color may vary from yellowish to pinkish or
gray. For more information on alfalfa wilts and rots check out
our online publication: Alfalfa
Rots and Wilts
nodorum blotch- Small Grains
Wise, NYS IPM
the Cornell Research Farm in Valatie, I discovered stagonospora
nodorum blotch on the lower leaves in Tom Kilcer’s triticale plots.
Splashing rain or thunderstorms can move spores from field surface
to the plant wheat seed can be contaminated from spores when it
is harvested. This disease may also be in the residue on the surface
of the field. Greatest yield losses occur when the flag leaf and
the next two lower leaves become infected by the time the wheat
flowers in late May. Symptoms usually appear within two or three
weeks of head emergence. Leaf lesions begin as very dark brown
flecks or spots, sometimes with a yellow halo. These small irregular
lesions expand into oval light brown lesions with dark brown centers.
On wheat heads the lesions begin as either grayish or brownish
spots on the chaff, usually on the upper third of the glume. As
lesions enlarge, they become dark brown and the centers turn grayish-white
in color as tiny brown or black dots (pycnidia) develop within
Degree Days in NYS
Waldron, NYS IPM
Growing degree days (48F Base)
1 - May 1, 2005
Clifton Park: 130.1
did the Dandelions get into the Alfalfa Field?
Wise, NYS IPM
walking alfalfa fields at the SUNY Cobleskill Farm this week I
came across many dandelions. If you think about this, every place
that a dandelion was growing was one less place for an alfalfa
plant. The obvious consequence is a loss of yield and hay quality
potential. The bigger question is why? There are many potential
reasons weeds may encroach into alfalfa. Many times it is an older
alfalfa field that is slowly declining and allowing space for
other weeds to grow. An old stand? Disease or insect pressure?
Harvest Interval? Compaction? Fertility or pH? In the SUNY Farm
fields mentioned above there appeared to be a lot of frost heaving
and root & crown rot. This creates open space for dandelions
and other weeds to successfully establish.
field records: variety, planting date/rate, pesticides used, nutrient
inputs including manure, other important field observations,
wet spots in field for future drainage.
weevil, alfalfa snout beetle, weeds, crown rot
Wheat: Cereal leaf beetle, virus diseases, weeds
Grains: Cereal leaf beetle, seedling diseases, weeds
damping off / seedling blights, seed corn maggot
harvest start by May 15 (NY)
planting finish by May 15, if soil conditions allow
Stavisky: IPM Area Educator, Livestock and Field Crops,
Phone: (315) 331-8415
Fax: (315) 331-8411
Waldron: NYS Livestock and Field Crops IPM Coordinator
Phone: (315) 787 - 2432
Fax: (315) 787-2360
Wise: Eastern NYS IPM Area Educator: Field Crops and Livestock
Phone: (518) 434-1690
Fax: (518) 426-3316