Volume 13 Number 21
View from the Field
Jeff Miller (CCE Oneida County) reports northern corn leaf blight is widespread across Oneida County. He also states the infections are mainly along the edges of fields. Jeff Miller also reports severe crown rust in an oat cover crop.
Gray Bergstrom (Cornell University, Plant Pathology) reports northern corn leaf blight has been found statewide. Margaret Smith (Cornell University, Plant Breeding) is finding northern corn leaf blight, grey leaf spot and eyespot in corn.
So…… Is your corn showing any of these symptoms? ….can you identify the disease?
The first photo is northern corn leaf blight , the second photo is grey leaf spot and the third is eyespot. If you have found these diseases in your corn make a note of it. “RECORD IT”! It will help you make decisions in the future on selecting hybrids that are more resistant. You may also decide to rotate the corn out of a field that had an infection. Keeping records on pest issues is very important relative to making your IPM plan for the future!
Weather Outlook – September 25, 2014
NOAA Northeast Regional Climate Center, Cornell University
Last week temperatures ranged from 2 to 6 degrees below normal for most areas. Precipitation ranged from a trace to an 1 inch. Base 50 growing degree-days ranged from 10 to 70.
Warm & Sunny!
Low pressure moving up the coast will bring showers and possibly some scattered thunderstorms to southeast NY, the rest of the state will stay dry and partly sunny. Temperatures will range from mid-60’s to mid 70’s. Overnight temperatures will be in the low 40’s to low 50’s. Friday will be sunny and dry with highs throughout the 70’s. Low temperatures will be in the upper 40’s to low 50’s. Saturday will be sunny with highs in the 70’s with some areas possibly reaching 80. Overnight temperatures will be in the mid 40’s to low 50’s. Sunday will be sunny with temperatures in the 70’s and some low 80’s. Overnight temperatures will be in the upper 40’s to mid 50’s. Monday will be partly cloudy with highs in the mid 60’s to low 70’s with a slight chance of showers. Overnight temperatures will be in the upper 40’s to low 50’s. Tuesday will be partly sunny with highs in the mid 60’s to low 70’s with scattered showers possible. Lows will be in the 50’s. Wednesday’s highs will be in the mid to upper 60’s with scattered showers. Lows will be in the upper 40’s to low 50’s. The five-day precipitation amounts will taper from around 1” in extreme southeast NY to nothing in the Central Lakes/Northern Plateau and beyond. The 8-14 day outlook (Oct 2-8) is showing above normal temperatures and above normal precipitation for all but eastern NY. October and Oct/Nov/Dec outlooks are showing above normal temperatures, no indication for precipitation. There is still an abnormally dry area covering part of the Catskills and southern Hudson Valley.
Look For Stalk Rots
Ken Wise, NYS IPM
Stalk rots are normally a complex of different diseases and factors working in the corn plants. Many times stalk rots occur when you have multiple stresses on the corn plants at the same time over the course of the growing season. This could be the combination of environmental factors, soil nutrition, diseases, insect pests, available moisture and more. When a plant is stressed in more ways than one it is more vulnerable to diseases like stalk rots. There are many different fungi and bacteria that can cause stalk rots. Many of these diseases can survive on past corn crop residue or even in the soil. Stalk rots normally enter the plant through the roots but can enter other ways like insect pests boring into the stalk leaving an open hole for pathogens to enter the plant through wind or rain. Stalk rot causes premature death of the corn plant by attacking water conducting tissues of the roots and lower stalks. As it progresses the fungi moves up the pith of the plant. The cells in the pith of the plant are thinner and much easier for the disease to attack than from the outside. This limits the plant from moving water and nutrients. The rot will weaken the stalks and plants can start to lodge. While each species of stalk rots have specific symptoms they do have a few that are in common.
- Leaves may be wilted or roll and start to turn brown.
- An entire field may appear to be killed by a frost because the disease does not allow water and nutrients to move through the plant
- Lesions will appear on lower nodes and/or on entire stalk
- Stalks become soft (healthy stalks are firm). With advance stages of rot the stalk can be easily crushed with your fore finger and thumb.
- Stalks can lodge with a weather event.
The following are specific types of stalk rots found in NYS:
|Common Name/Species||Symptoms||Link to photos|
|Anthracnose stalk rot/ Colletotrichum graminicola||Symptoms often show after tasselling as vertical, tan to reddish brown, water-soaked lesions (streaks) in the stalk rind. Lesions become large and dark brown to shiny black. If you see anthracnose leaf blight, check for anthracnose stalk rot—both diseases share the same causal agent.||Anthracnose stalk rot|
|Diplodia stalk rot/ Stenocarpella maydis||Symptoms appear as numerous black pycnidia (a saclike spore case) in the lower internodes of the stalk. The cases are black dots size of a pinhead or smaller. Look for a white mold on the stalks when weather is wet||Diplodia stalk rot|
|Fusarium stalk rot/ Fusarium spp.||This disease normally starts just after pollination, with symptoms appearing later in the season. When you cut open the stalk, the pith shows as a whitish to pink (salmon) color. Look also for distinctive brown streaks on the lower internodes.||Fusarium stalk rot|
|Gibberella stalk rot/ Gibberella zeae||This disease shows first as leaves fade to a grayish-green. Stalks turn dark green to tan near their bases. The pith softens, turning reddish or pink||Gibberella stalk rot|
|Pythium stalk rot/ Pythium aphanidermatum||This disease normally appears as a decay of the first internode above the soil. The pith will become soft, turn brown and appear water-soaked. Many times the stalk can twist and/ or lodge. Even though it may have lodged the plant will stay green for several weeks because the vascular tissue is not destroyed.||Pythium stalk rot|
There are management practices you can do to limit corn stalk rots in your fields.
- Plant hybrids that are resistant to the diseases. Remember that corn can be resistant but never immune.
- Use of crop rotation is a good way to limit the diseases from infecting the corn. Many of these diseases survive on corn residue. By planting corn in the same field each year you increase the risk of getting an infection.
- Use proper plant populations. If a field is planted at too high of a population the corn will compete for nutrients and water. This adds more stress to the plant and an increased risk of getting an infection.
- Maintain good soil fertility and pH. By maintaining good soil fertility and pH helps keep corn plants healthy and reduces stress on the plants.
- Proper cultivation. If you cultivate, it is important not to damage the roots or the plants. If they are damaged it increase the pathways for disease to infect the plants.
- Tillage can help reduce the available disease in the field by burying residue. While tillage can help it is not a guarantee control. Plus the need to reduce erosion and save on soil moisture maybe more important.
Keith Waldron, NYS IPM
*Walk fields to check general field condition, weed or other issues
*Watch for crop maturity, stand assessments, weed escapes, lodging issues
*Evaluate established legume stands for approximate days until harvest
*Monitor potato leafhopper
*Monitor new seedings for potato leafhopper, pythium blight, phytopthora root rot.
*Monitor spring grain fields for growth stage, disease issues, harvest timing
*Prepare for planting of winter wheat
*Monitor fields for plant vigor, growth stage, late season pest issues (European corn borer, western bean cutworm, foliar diseases, nutritional deficiencies, vertebrate damage)
* Monitor for weeds, note presence of “who”, “how many” and “where”
* Monitor reproductive stage corn fields for foliar diseases, stalk standability issues, corn ear damage (insect pests and diseases), grain maturity.
*Be on the lookout for possible larval feeding by Western Bean Cutworm in corn ears (and dry bean pods)
* Prepare storage areas to accept upcoming silage harvest
*Conduct late-season soybean pests such as soybean aphid, white mold, soybean vein necrosis virus and other diseases, weed issues, vertebrate damage
*Monitor for late season infestations of Brown Marmorated Stink Bug around field margins
*Check crop growth
*Review/Plan rotation system
*Check and mend fences as needed.
*Invasive species, plants harmful to livestock
*Cleanand sanitize empty grain bins in advance to receive upcoming soybean or corn grain harvest
*Check forage allocation and anticipate feed program adjustments as forages from previous year are used up
*Plan where forages should be stored for optimum allocation next feeding season
*Mow around storage bins and facility to minimize harborage and pest hidingplaces
*Check stored grain bins for temperature, moisture and signs of mold and insects. Aerate, core, transfer grain or treat as necessary
Dairy Cattle Barn Fly Management:
*House and stable fly populations can increase in barns as outside dwelling flies seek shelter during cooler weather. Increase vigilance to minimize fly breeding habitat
*Monitor animals and barn area for house fly, stable fly and other pest management needs including presence of rodents and birds.
*Check facilities for favorable fly breeding conditions: (organic matter + moisture): leaks in watering systems, roof gutters for leaks and potential overspill, drainage,
*Sanitation, sanitation, sanitation – clean animal resting areas, feed troughs, minimize source of moist organic matter i.e. fly breeding areas in barn and in adjacent animal loafing yard
* Continue fly monitoring: install “3X5″ index card fly speck monitoring cards throughout barn
*Use, replenish, replace fly management materials: sticky fly tapes/ribbons, insecticide baits, natural enemies (parasitoids), fly population monitoring (3 x 5) spot cards
*Consider purchase and release of Muscidifurax raptor and/or M. raptorellusnatural enemies of house and stable fly pupae.
Dairy Cattle on Pasture:
*Monitor animals for presence of face flies, horn flies and stable flies. Action guidelines: face flies (average 10 per animal face), horn flies (average 50 / dairy per animal side, 200 / beef cattle per animal side), stable flies average 10 per animal (all four legs)
*Check feed bunk / water source locations for signs of stable fly breeding (moist undisturbed organic matter – spilled feed, round bales, etc.), minimize source of moist organic matter i.e. fly breeding areas in barn and in adjacent animal exercise yard.
*Check pasture for forage quality / quantity, rotate as appropriate
*Check pasture for vegetation poisonous to livestock
*Consider use of pasture fly traps to help reduce deer, horse and stable fly populations
*Check and prepare equipment for upcoming harvests
*Maintain pesticide use records