Volume 16 Number 14
View from the Field
While potato leafhopper (PLH) seems to be declining from very high infestation levels there are still many fields being reported over threshold. I was seeing a lot fewer nymphs in fields in Valatie this week. Where alfalfa that was less than 7 inches tall there were not many PLHs. In taller alfalfa PLH was still over threshold.
Paul Cerosaletti (CCE Delaware County) reports finding corn rootworm damage in corn. The following photos show the damage that can occur. Corn rootworm is a wormlike beetle larvae that feeds on corn roots. It hatches from eggs laid in the soil the previous summer. Corn rootworm has a white body and brown head, about the diameter of a pencil lead. They start feeding on corn roots about the same time as you start to see fireflies in June. Corn rootworm can reduce the plant’s ability to get water and nutrients from the soil, thus significantly reducing yield of silage and grain. Heavy feeding can even cause lodging (sometimes called goose-necking). Goose-necking is the plant’s attempt to straighten up again after it has begun to lean or lodge.
Mike Hunter (CCE Northern NY) reports infections of white mold in soybeans. This might be a year that we see a lot of white mold in soybeans with the excess rain and moisture we have received. For more information see article below. Mike also reports a few fields over threshold for western bean cutworm egg masses and young larvae. These fields were sprayed with and insecticide.
Weather Outlook – August 3, 2017
NOAA Northeast Regional Climate Center, Cornell University
Last week temperatures ranged from 4 degrees below-normal to 2 degrees above-normal. Precipitation ranged from less than a quarter inch to over 1 inch. Base 50 growing degree-days ranged from 70 to 150.
Showers & thunderstorms Thursday & Friday, drying out for the weekend before unsettled weather returns on Monday.
Today temperatures will be in the mid to upper 80’s with humid conditions and scattered showers and thunderstorms. Isolated heavy rain, strong winds, and small hail is possible. Overnight lows will be in the 60’s.
Friday temperatures will throughout the 80’s, with showers and thunderstorms likely as a strong cold front moves through. Heavy rain associated with this front is possible Friday into Friday night, as well as damaging wind, hail and dangerous lightning. Overnight temperatures will be in the 60’s.
Saturday’s highs will be notably cooler, in the 70’s with a slight chance of showers, mostly in eastern NY as the cold front slowly exits the state. Overnight temperatures will be in the mid 50’s to low 60’s.
Sunday will by sunny and dry with highs in the 70’s. Overnight temperatures will be in the mid 50’s to low 60’s.
Monday’s highs will be in the 70’s with scattered showers possible. Heavy rain is possible Monday into Tuesday for some areas of the state. Lows will be in the mid 50’s to low 60’s.
Tuesday will have temperatures in the mid 70’s to low 80’s with isolated showers and thunderstorms possible. Lows will be in the mid 50’s to low 60’s.
Wednesday, temperatures will be in the mid 70’s to low 80’s with isolated showers and thunderstorms possible. Lows will be in the mid 50’s to low 60’s.
The seven-day precipitation amounts will range from 1 ¼” to over 3”.
The 8-14 day outlook (Aug 10-16) favors below-normal temperatures for all but the eastern edge of the state; favors above-normal precipitation.
IPM for weeds in unplanted fields
Bryan Brown, Ph.D., NYS IPM
Due to the wet weather, many fields did not get planted this spring. The lack of management has allowed weeds to really take off.
The danger is that the weed seed production could cause a disaster in the next few crops. In my research, plots where weeds went to seed resulted in 10 times the amount of weeds the following year. Also, if any of the weeds are herbicide resistant, they’d be depositing thousands of herbicide resistant seeds into your fields.
But it’s not too late – many weed species have not yet gone to seed. Mowing is a great option to quickly prevent the flowering weeds from setting seed. It can buy you some time but most weeds will continue to send up new flowers – some of them below the mower height. So it’s important to kill them with herbicides or tillage prior to summer plantings of cover crops, or fall plantings of forage or winter grains.
What if it is too late? Say you walk out into an unplanted field that’s filled with weeds and you find that most have set seed. What are your options to prevent that seed from causing a weedy disaster for the next year?
You could use a Combine to harvest the seeds and dispose of them. You could Mouldboard plow to put those seeds deep into the soil where they won’t germinate – this should only be done in extreme cases because you’ll also bring up seeds from the deep “cold storage” zone. You could mow to get those seeds on the ground where beetles, mice, and birds can eat them (until frost pulls the seeds into the ground). These seeds in the top layer of soil will be more likely to germinate in the next season, so a delayed planting might allow you to control many of these with burndown herbicides or tillage.
Keep in mind that, for many problem weeds, most of their seeds will die in the first couple of years, so it’s possible to get back on track if you prevent further weed seeds from entering your soil.
Photo Taken by Bryan Brown: Scouting to see if weeds have set seed. Prevention is an integral part of IPM.
White Mold Sclerotinia Stem Rot in Soybeans
Ken Wise, NYS IPM
The white mold fungus (Sclerotinia sclerotiorum) can be a very serious and problematic disease of soybeans. This fungus has a wide host range including: alfalfa, beans, canola, clover, peppermint, potato, sunflower and tomato. White mold can also attack certain weeds like amaranth, castor beans, dandelions, lambsquarter, ragweed and velvetleaf. In total there are about 400 different plant species that are susceptible to this disease.
The whole field can look very healthy with one or 2 plants apparently dead. The leaves will remain on the plant but the main stem will turn brown and then die. This disease thrives in dense stands where there is not much room between plants. If you combine a thick healthy stand of soybeans and cool damp weather can create prime conditions for white mold to take hold.
This soil-borne fungus overwinters in soil in a special structure called sclerotia. The structure looks like a dark hard mouse dropping. Sclerotia can survive msny years in the soil when there are no hosts present in the field. When the soil temperature is below 650 F, excess moisture and the sclerotia is within an inch of the surface small mushroom like structures grow. These are called apothecia and are 1/8” to ¾” in diameter. The top of the apothecia is cup like and is where spores are produced. The spores are ejected out of the cup area of the apothecia.
White mold spores infect the soybean plants at flowering. The spores land on the flower and germinate. Once spores germinate they can infect the plant through the dead or dying flower tissue near the node. After entering the plant the fungus consumes plant nutrients. In the end this will girdle the tissue around the stem killing all the tissue above that point.
Look for white, cottony growths and small, dark, round or elongated sclerotia on or within the stem. Some sclerotia can be about the same size as a soybean seed and may enter the bin with the seed at harvest. Most of the sclerotia fall to the surface to complete a cycle again in the future.
The infected stems and pods are pale brown and look water soaked. When conditions are right white mold can be very difficult to manage. Some research suggests that using a corn planter and leaving 30 inches between the rows allows for air to move around the plants. This helps keep plants drier at flowering. It also helps keep the soil surface drier and humidity to remain lower. This reduces the development of the apothecia or spores from being released.
Rotation is an important factor when dealing with white mold. NEVER plant soybeans directly after dry beans, soybeans or other susceptible plant species. This is like playing with fire when it comes to white mold. Always try to rotate with a non-host like corn, wheat, barley, grass hay, and so on.
If you do get an infection of white mold in a field it is important to not plant soybeans or dry beans back to the field for 3-5 years. It will help reduce future infections. If a field does get infected try to harvest this last. You can move sclerotia from field to field if you are not careful. If you do harvest a field with white mold before the others make sure to clean your combine very well before entering a non-infected field.
There are soybean cultivars now that have moderate resistance to white mold. When selecting a cultivar make sure it is one that is well adapted to the region where you live.
The population density of apothecia was greatest in moldboard plow systems compared to no-tillage systems. Fewer apothecia in no-tillage systems is a partial explanation why lower incidence of white mold is observed in no-till fields compared to fields receiving some degree of tillage.
Some fungicides help provide some suppression of white mold. The indeterminate growth habit of soybeans presents a challenge for disease control since the plant continues to flower – producing susceptible infection sites over a period of time. Good canopy penetration and proper timing are essential to get a limited amount of control. It seems that the fungicide works best when infection is moderate.
To manage white mold in soybeans, combine rotation, row spacing, resistant cultivars, tillage, and possibly fungicides where conditions are favorable.
Western Bean Cutworm Update 8.4.17
Western Bean Cutworm is approaching peak flight in the next few weeks. We has more than two times as many moths caught from the previous week.
|Avg WBC / Trap||0.4||0.5||1.2||4.0||37.3||109.4|
|> 0 WBC||4||7||18||30||45||44|
|% Traps Catching||25.0%||25.9%||36.7%||57.7%||90.0%||100.0%|
|Accum Total forSeason||7||22||83||324||2303||7118|
NYS Degree Days
Keith Waldron, NYS IPM
*Walk fields to check general field condition, weed, vertebrate and other issues
*Watch for crop maturity, stand assessments, weed escapes, nutrient deficiencies, lodging issues
*Evaluate established legume stands for approximate days until harvest
*Monitor potato leafhopper, foliar, systemic and crown rot diseases.
*Monitor new seedings for potato leafhopper, pythium blight, phytopthora root rot.
*Monitor grain fields for growth stage, disease and lodging issues, grain maturity, harvest timing
*Record diseases present, location and types of weed escapes
*Monitor for mid-season corn pests including European corn borer, corn rootworm, western bean cutworm, slugs, foliar diseases such as northern corn leaf blight and gray leaf spot, weed issues, nutrient deficiencies, vertebrate damage.
*Monitor for soybean aphid, defoliators, foliar diseases, white mold, weed issues, vertebrate damage
*Check water sources, mend fences as needed.
*Check crop growth, clip pastures between grazing as needed
*Monitor for invasive species, plants harmful to livestock
* Check stored grain bins for temperature, moisture and signs of mold and insects. Aerate, core, transfer grain or treat as necessary
* Clean and disinfect empty storage bins in preparation for grain harvest
*Check forage allocation and anticipate feed program adjustments as forages from previous year are used up
*Mow around storage bins and facility to minimize pest hiding places
Dairy Cattle Barn Fly Management:
*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. raptorellus natural 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