Weekly Field Crops Pest Report 2008
View from the Field
Jeff Miller reports an excessive amount of downy mildew infesting soybeans fields in OneidaCounty. Many extension educators are reporting more white mold in soybeans this week. Mike Hunter ( JeffersonCounty) reports many soybean fields have high infestations of white mold. I also discovered areas of white mold in the soybean sentinel plot in ColumbiaCounty. There was also a significant increase in the infestation levels of soybean aphids in the sentinel plot. There was from 0 to 80 aphids/plant and an average of 32 aphids/plant which is still far below threshold.
This week I saw an excess of corn ear damage caused mostly by black birds, but also deer at the SUNY Cobleskill farm. The husk covering the corn was pulled back and about a 1/3 of the grain was gone.
Weather Outlook 9.4.08
Last week brought slightly above normal temperatures to the state. The western Southern Tier was about a degree below normal while the rest of the state averaged about a degree warmer than normal.
Between 90 and 150 Base 50 degree days accumulated across NY last week with the highest totals on Long Island and the lower values in the western Southern Tier and Adirondacks. Across NY seasonal totals range from 1800 in parts of the Southern Tier to 2000 near the Lakes and in the Albany area, with 2500 on Long Island. These accumulations are within a week of last year’s early September accumulation and also between 0.5 and a week ahead of normal. At this time of year about 100 GDD typically accumulate in a week.
All locations east of Ithacasaw less than a half an inch of rain with many places seeing no rain. Between 0.5 and 1 inches fell in and around New York Cityand a across the western Finger Lakes.
A very active week of weather is in store for New York. Friday looks to be warm and humid as the tropical air associated with both Gustav and Hanna move into the region. The day will be generally rain-free, but the chance of showers and thunderstorms will increase from late afternoon through the night. Saturday appears to be the time frame that the rainfall from Hanna will affect NY. Expect periods and areas of heavy rain through Saturday night. Places in Hudson Valley and around NY City may see in excess of three inches of rain. To the west, Buffalo may only see a few tenths, with perhaps as much as an inch in Binghamton. To the east the rain may persist into Sunday. Most of the state will see seasonable (highs in the upper 70s and low 80s lows in the 50s) and dry weather through Tuesday when cold front moves through bringing the next chance of showers. At this point this front should push the moisture from Hurricane Ike to our east on Wednesday. Temperatures will be mostly in the 70s during the day and in the 50s at night.
Beyond Wednesday the pattern will tend to bring cooler than normal and wetter conditions to the state.
Fall Weed Management in Winter Wheat
Weed maps and records from field observations should be reviewed now as wheat planting is getting underway. The most important weed threats in the fall are the winter annuals that establish in the fall as wheat seedlings emerge and begin to grow. Winter annuals include chickweed, purple deadnettle, shepherd’s purse, henbit, and corn chamomile. The weeds and wheat are actively growing on warm fall days, and they compete for nutrients and water. Severe weed infestations can interfere with the wheat’s ability to establish a healthy stand in the fall.
Corn chamomile is especially difficult to control in the spring, but can be controlled with a fall herbicide application when rosettes are still very small. For more information, please visit the Weed Control in Small Grains section of the 2008 Cornell Guide for Integrated Field Crop Management.
Hessian Fly Management in Winter Wheat
Hessian fly is an insect pest that can attack of winter wheat seedlings in the fall. Hessian fly adults are similar in appearance to a mosquito but smaller in size. Adult female flies lay small orange colored eggs in lines on the upper surface on young leaves between the leaf veins.
Larvae hatch in the fall and feed between the stem and leaf sheath near the base of the plant in newly established wheat. The larvae pupate (flaxseed stage) and over-winter in the plant. In the spring, adult flies emerge from the "flaxseeds" and lay eggs on the leaves. Upon hatching, the maggots work their way under the leaf sheath near the node. Damage during the fall causes stunting of the new plants; the spring and early summer damage results in unfilled heads and fallen straw. Their feeding weakens the stem which causes the stalks to break and lodge before harvest.
One of the best methods to minimize risk of a Hessian fly problem is to plant winter wheat after the Hessian fly free date. Beyond this date Hessian fly is not expected to be a threat to local winter wheat. The actual Hessian fly free date varies with geographic region and altitude. See the small grains section of the Cornell Field Crops Guide for the Hessian fly free date in your area. Other methods of management are to control volunteer wheat by plowing under stubble at least 6 inches deep. The use of Hessian fly resistant cultivars has been used in the past. Unfortunately, some Hessian fly biotypes are able to overtake this resistance. Check with your source for wheat seed to see if resistant varieties are available for your area.
Soybean Rust Update
Sentinel plots in New York State have been established in the following counties: Cayuga, Chautauqua, Chemung, Columbia, Cortland, Jefferson, Lewis, Madison, Niagara, Oneida, Ontario, Schoharie, Seneca, Steuben, Wayne and Yates. Plant growth stages in these plots range from R-2 to R-6. Mid to high levels of Septoria brown spot and downy mildew were detected in several of the sentinel plots across NYS last week.
Soybean rust has been detected in two new states over the past week. On August 22nd, soybean rust was detected on soybean in a research plot in Decatur, Georgia. On August 24th, soybean rust was reported in a commercial field at the R8 growth stage in Willacy County, Texas.
Since the beginning of 2008, soybean rust has been reported on kudzu in two counties in Alabama; four counties in Georgia, eighteen counties in Florida (two of these counties had reports on coral bean and snap bean and one had a report on soybean); three counties in Louisiana; three counties in Mississippi, and five counties in Texas. Reported infected kudzu sites in many counties have been destroyed. Rust was also reported in three states (5 municipalities) in Mexico on yam bean and soybean. These too have been destroyed or are no longer active. (Updated August 26, 2008)
NY State Soybean Rust Hotline: 607-255-7850
Soybean Aphid Update
Soybean aphid (SBA) populations remain low again this week across NY, although some increases in populations were observed in a sentinel plot in eastern NY. Reports indicate monitored fields are typically averaging 0 to less than 5 SBA's per plant at this time. The eastern NY sentinel field had an average of 34 SBA’s per plant with up to 80 SBA’s observed in R6 stage soybeans. All fields reporting were still well below threshold. Natural enemy populations, such as ladybird beetles, are present in most areas.
Crop Growth Stage –
Soybeans are generally in mid to later reproductive stages. Some fields in the central southern tier are approaching full maturity. Soybean heights vary from 16 inches to 30 plus inches tall.
Soybean aphid scouting and management –
Low soybean aphid numbers typically observed pose negligible risk to soybean yields. Close inspection of fields is still the most reliable source of individualized field information on which to base potential insecticide use decisions. Risk of SBA damage to yields decreases as plants mature. No SBA threshold is available for R6 stage soybeans. Research has shown no economic return on insecticidal applications during the R7 and R8 growth stages.
The national USBRUSA.net website last week reported soybean aphid populations were a concern in Wisconsin, Minnesota, North Dakota, South Dakota, N. E. Nebraska, northern Iowaand Illinois. In those states soybean aphid populations have warranted two insecticide treatments in some areas. By contrast, soybean aphid numbers remain low in New York, Ohio, Indiana, much of Michiganand the southern half of Illinois.
It is possible that the predicted movement of hurricanes Gustav and Hannah this week may carry SBA’s eastward from infested areas of the Midwest. Growers are encouraged to monitor soybean fields for presence of soybean aphids, other insects, and diseases.
Soybean aphid management decisions should be based on a field visit and SBA population assessment. The national soybean aphid management recommendations, including the recommended soybean aphid action threshold for R1 (beginning bloom) through R8 (full maturity) reproductive stage soybeans are:
R1 to R5 growth stages
During the period when the soybean crop is reproductive (i.e. flowering) in the R1 to R5 growth stages, an insecticide application may be necessary when 250 or more aphids occur per plant and approximately 80% of the field is infested and populations are increasing. Sequential scouting in the same field is necessary in order to determine if populations are increasing. Comparing SBA counts over a week or more is necessary.
A higher threshold is required for economic return during the R6 growth stage, but no threshold data is available at this time. If treatment options are considered, ensure pre-harvest intervals of the insecticidal product chosen are met prior to application.
R7 growth stage and later (beginning maturity to full maturity).
During the R7 and R8 growth stages, there is no economic return on insecticidal applications.
For more information see: USDA Public PIPE Website: Management Toolbox - Guidelines - USA
* Emergency contact information ("911", local hospital, Chem. Spill emergency contact, other?) posted in central posting area
* Maintain crop records by field, including variety, planting date, pesticides used, nutrient inputs including manure, yields, etc.
* Watch for weed escapes, any patches of herbicide resistant weeds?
* Prepare bunkers, silos for incoming silage.
* Mow around storage bins, barn and farm facilities
* Note presence of potentially invasive weed species such as black and pale swallow-wort, common buckthorns, garlic mustard, japanese honeysuckle, japanese knotweed, multiflora rose, purple loosestrife, and spotted knapweed
Alfalfa & Hay:
* Monitor alfalfa seedings for weeds, for potato leafhopper & diseases.
* Check established alfalfa stands for potato leafhopper, weed encroachment and disease problems.
* Storage areas cleaned and ready to accept next harvest?
Check grain storage bins for temp, moisture, air flow, drying conditions.
* Plant winter wheat after Hessian Fly-free date
* Note crop growth stage and condition
* Check for European corn borer, armyworm, foliar and stalk rot diseases, vertebrate injury (birds / deer), weed escapes, herbicide injury, nutritional deficiencies, etc.
* Check corn for grain fill issues – mold, insects, vertebrate damage
* Monitor weed populations noting presence of "who", "how many" and "where"
* Harvest corn silage at 65 to 68% moisture and high moisture shelled at 25 to 30% grain, and high moisture ground-ear at 30 to 35% moisture.
* Record corn silage yields by field and quality by storage area, take samples for forage analysis
* Take Soil Samples for fertility analysis
* Take Fall Weed Survey following harvest.
* Note crop growth stage and condition
* Evaluate stand for soybean aphid, white mold, foliar diseases, sudden death syndrome (Fusarium solani f. sp. glyines), and brown stem rot (Phialophora gregata f.sp. sojae)
* Harvest when soybeans reach safe storage moisture level of approximately 13%.
* Review combine settings and speeds to minimize seed damage
Dairy Cattle: Livestock Barn Fly Management:
* Monitor animals and facilities for house fly and stable fly populations
* 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 through out barn
* Use, replenish, replace fly management materials: sticky fly tapes/ribbons, insecticide baits, natural enemies (parasitoids), fly population monitoring (3 x 5) spot cards
Dairy Cattle: Pasture Fly Management:
* 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, 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 loafing yard
* Check paddocks for forage quality / quantity, rotate as appropriate
* Check paddocks for vegetation poisonous to livestock
* Consider use of fly traps to help reduce deer, horse and stable fly populations
* Pre-clean in and around grain storage bins in anticipation of soybean and grain corn harvests.
* Keep areas around storage bins and silos clean and mowed
* Provide annual maintenance to manure, fertilizer, and pesticide application equipment
* Prepare combines for corn, soybeans
* Sharpen chopper knives. Check shear clearances, protective shields
* Note any repairs to harvesting equipment as they are cleaned and lubricated.
Keith Waldron: NYS Livestock and Field Crops IPM Coordinator
Ken Wise: Eastern NYS IPM Area Educator: Field Crops and Livestock