Field Crop News

Website Address: http://fcn.agronomy.psu.edu/

July 22, 2005    Vol. 05:09

IN THIS ISSUE:

Mark Your Calendar

Weather Outlook

Production

Pest Management

Agents Corner

WEATHER OUTLOOK

The combination of rain from Cindy and thundershowers from Dennis has raised the monthly rainfall to above average in the southeastern third of the state. Even the northern and central mountains have received near normal rain so far in July. Only the western third of Pennsylvania is averaging below normal rain (less than an inch). Temperatures continue well above seasonal levels, especially at night. Cloud cover has been a bit more extensive, but sunshine remains above normal too. Light winds (less than 10 miles an hour) have been the rule so far this month.

A series of cold front will pass through the Northeast during the coming week. One front early in the weekend will trigger showers in about half the state and be followed by less humid, but seasonably warm conditions. The return of very sultry air early next week (July 25-26) may be marked by potent and perhaps isolated severe thunderstorms. A push of cooler and less humid air mid-week (July 27-28) should initiate a few thunderstorms. There are indications that the weather pattern will switch to a cooler, damper regime for the first week of August.

Odds still favor the hottest weather of the summer coming during the middle or later half of August. Rainfall is expected to average below normal in the western half of Pennsylvania and above average in the eastern sections. The autumn should turn wetter, especially in October.

Paul Knight, pgk2@psu.edu
Pennsylvania State Climatologist

PRODUCTION

ACRE SIGNED IN TO LAW

Last year at Ag Progress Days Governor Rendell unveiled the "Agriculture, Communities, and Rural Environment" (ACRE) program. On July 6, 2005 the Governor signed this program into law as Act 38 of 2005. This act will significantly impact agriculture and rural communities by coordinating existing laws and regulations, primarily the "Right to Farm" Law and the Nutrient Management Act, with several new initiatives.

The main purposes of Act 38 are to ensure that local governments enact ordinances regulating normal agricultural operations that are consistent with authority given them by the laws of this Commonwealth to protect citizens' health, safety and welfare. It provides for timely review of potentially unauthorized local ordinances by the state Attorney General who will then decide whether to take legal action on an ordinance.

The law also replaces the Nutrient Management Act (Act 6). However, most of Act 6 is retained in this law and remains in effect, including the focus on concentrated animal operations (CAOs), all existing and revised regulations, all prior and ongoing plan approvals, and financial assistance commitments. The new law does add a mandatory 100 ft manure application setback on CAOs unless there is a 35 ft vegetated buffer next to the water. It also will require new or expanding CAO or CAFOs to have an approved odor management plan.

A fact sheet providing details on the provisions of Act 38 has been developed and is available on the web at the Penn State Cooperative Extension, Nutrient and Water Policy Update website: http://agenvpolicy.aers.psu.edu/ACREnewfinal.pdf.

Douglas Beegle, dbb@psu.edu
Soil Fertility, Crop and Soil Sciences

MOISTURE CONSERVATION STRATEGIES

This season is quite different from the past two years with dry conditions in many parts of the state (see Table 1). Low May precipitation in some parts resulted in little stored soil moisture at the beginning of the summer. Summer rainfall has also been lacking in some parts. Additionally, summer rainfall often comes as high-intensity convectional rainstorms, especially in the south of the state. For example, on June 6th, 4" of rain fell at the Lancaster Airport, 70% of that month's precipitation. These large rainfall events typically cause more runoff, water that is lost to the crop. Because evapotranspiration of a crop such as corn is typically 1/5 of an inch/day in the summer, moisture stress is evident in many places. Droughts frequently hit our state, and growers can prepare using these strategies to reduce drought risks:

Field corn showing leaf-curling, an indication of drought stress.
Table 1. This year's and average precipitation in Lancaster, Dubois, and Meadville
Month 2005 precip. (") Average precip. (')
Lancaster
May 1.0 4.5
June 5.7 3.5
July 6.5 4.5
Dubois
May 1.5 3.9
June 3.1 4.7
July 2.7 4.1
Meadville
May 1.2 3.8
June 3.1 4.4
July 2.2 4.4
  1. Maintain residue cover

    Residue cover is a most effective means of moisture conservation. Residue protects the soil surface against raindrop impact which helps to increase infiltration. It also acts as a protective barrier reducing evaporation of water from the soil surface. The best way to maintain residue cover is to no-till into crop residue of last year's crop or of a cover crop.

  2. Improve soil structure

    Soil structure is the arrangement of soil particles in small aggregates, called aggregation. If soil aggregates are stable, they don't slake quickly, and the soil maintains good porosity. That helps to avoid soil sealing and crusting and improves water infiltration. Soil structure can be improved by eliminating or reducing tillage, increasing soil organic matter content, and maximizing soil occupancy with fibrous roots that hold soil particles together.

  3. Increase organic matter content

    Organic matter acts as a sponge and helps to increase the amount of water the soil can hold and release for plant growth. Organic matter content can be increased by good soil management practices such as no-tillage, cover cropping, adding compost or packed manure, and growing high-residue crops.

  4. Optimal management of cover crops

    Two principles are important: living cover crops consume water, whereas dead cover crops preserve water because of the mulch cover they provide. Thus cover crops should be killed approximately 2 weeks prior to main crop establishment, but should produce maximum residue to provide a thick mulch. Early fall establishment of cover crops assures higher biomass early in the spring. Increasing seeding rates of cover crops is another strategy to increase biomass production.

  5. Optimal weed control

    Weeds compete with crops for water so they need to be absent to reduce water competition.

  6. Avoid summer crop establishment after first cutting of hay

    This is the scenario where moisture stress shows up most evidently because the hay crop depleted soil moisture, while no mulch is present to preserve soil moisture in the summer. It is therefore recommended to fall-kill a hay crop.

  7. Avoid soil compaction

    In our research on well-drained soils we have observed the worst compaction effects in dry years because of two reasons: (1) Crop establishment was endangered in the hard soil surface, an (2) root growth was inhibited. With a reduced root system, crops cannot explore a large soil volume for water, resulting in increased moisture stress. Soil compaction should therefore be reduced as much as possible.

  8. Spread corn planting window or plant corn with different tasseling dates

    Corn is most sensitive to drought at the time of pollination. If tasseling dates are spread out on the farm, drought risk is reduced.

  9. Plant a mix of winter and summer crops.

    Although monthly precipitation is approximately uniform in Pennsylvania, evapotranspiration is much smaller in the winter and early spring. Winter crops therefore commonly suffer less from moisture deficit.

Sjoerd Duiker, swd10@psu.edu
Soil Fertility, Crop and Soil Sciences

PEST MANAGEMENT

INSECT ALERT

Grasshoppers - In some areas of the state, we are seeing very high numbers of nymph stage grasshoppers. It is during these stages that the populations can experience high levels of mortality from diseases and predation. When nymphal populations are high you will see small areas of the leaf consumed. As the nymphs increase in size and then become adults they will increase their feeding rate and can cause significant defoliation of soybeans along the field edge. Seldom do they cause significant damage across the entire field, unless it is very narrow or small. In soybeans, the plants can tolerate up to 25% defoliation during the pod filling stage (R5) without having economic damage. Earlier and later stages require 35% defoliation. Estimating the percentage defoliation can be difficult because 25% defoliation looks more like 50% to the eye, so to an observer a field with 25% of the foliage removed will look pretty bad. The soybean plant can tolerate this level of damage because it is indeterminate and continues to bloom and put on new pods throughout its entire growth period. If a growing tip is injured, the plant will branch out.

As a guideline in soybeans, control may be justified if there are 20 or more grasshoppers per square yard in the field margins prior to their migration into the soybean field. For alfalfa, 0 to 3 grass hoppers per square yard is considered very light, 4 to 6 light, 7 to 14 threatening, 15 to 28 severe and 29+ very severe.

Unless the population is uniform across the field, an edge treatment will most likely eliminate or bring the numbers down below economic levels. See Agronomy Guide for up-to-date control recommendations.

Potato leafhopper - Population continues to remain high across the state. Watch new regrowth after the second cutting is removed.

Soybean Aphid - Reports of economic populations of soybean aphid have been coming in. We are still early in the historic population growth period so the next three weeks should see a rapid increase in numbers. Therefore, it is very important to watch soybean fields closely for the pest. The current economic threshold is 250 aphids per plant. When this population is reached, soybean aphid populations can increase up to ten fold (2,500 per plant) within a week. At the Russell E. Larsen Research Center near Rock Springs, PA the populations are just beginning to increase. As in previous years, if natural enemy populations (ladybugs) are high in the field, they should be able to prevent economic buildup of the population.

See the Agronomy Guide for management options.

Corn Rootworm - Larval feeding of corn rootworm is completed across most of the state, with only the most northern areas still having some larvae present. Adult emergence has begun in most regions, with the south and southeast being past peak emergence. Scouting should begin when at least 10% of the female's abdomens are swollen beyond the wing pads and if pressing between the fingers causes eggs to protrude. For western corn rootworm the economic threshold is 1.5 per plant in continuous corn and 1.0 per plant in first year corn. These numbers should be doubled for northern corn rootworm populations.

Spider-mites - The dry, hot weather during June started spider mite population buildup in soybean fields in some areas of the state. The pest is normally only a problem under dry conditions and populations typically drop off rapidly when significant rains occur. This is due to two things: 1) the rain directly washes the mites off the plants and 2) a fungal pathogen that the moisture allows to cause an epidemic in the population. However, even if the rains reduce populations they do not completely eliminate the population. Once dry, hot conditions return the population will begin to grow. At 90°F, spider mites complete a generation in about 7 days, compared to close to 21 days at 70°F. Almost all mites are female and each has the capability of producing 300 offspring. This is why populations increase so rapidly when mites are present in dry, hot years.

Look for yellow stippled plants that are not vigorously growing. On the underside of the leaves you will see very small (1/60 inch) orange, white, green, or red, eight legged mites with two dark spots on their back. They are typically actively moving around and you will see whitish cast skins on the leaf. When plants are severely damaged they can die.

See the Agronomy Guide for up-to-date control recommendations.

Dennis Calvin, dcalvin@psu.edu
Entomology

Agents Corner

Capital

Corn - Early plantings at R1 later plantings just entering R stages (about 2 weeks behind normal). Short crop height meaning shortened internodes.

Soybeans - Early plantings in R3 (flowering occurred earlier than normal this season) later seedings beginning to flower. Short as well with more prevalence of growth regulator drift this season.

Small Grains - Harvest reports in the 100 bu/acre with before rain test weights of 63 wich dropped to 58 after the rain.

Alfalfa - Third cutting should be harvested by this publication date. Leafhoppers took weeks to build in population but did after storms and were sprayed in many cases the last two weeks.

Pastures - Dry conditions early set back pasture growth. Many growers penned animals and supplemental fed. Recent rains have brought grass back into production. Anthracnose infested some pastures this spring.

Forage Supply - Many growers reporting the need for more forage as grass and alfalfa yields are behind for the season.

Straw - short wheat and barley straw yields sparked the straw market. Many producers selling directly out of the field. In some cases oats are being recropped after wheat for additional straw.

Grain Supply - Both barley and wheat yields were normal this year. It appears that producers will have ample grain supply.

Insect - Bean leaf beetles, soybeans aphids, grasshoppers, rootworm beetles, and spider mites all infesting fields. Where 30% leaf area is lost applications are being made. Many rootworm larvae escaped seed delivered pesticides but recent rains allowed for the roots to regenerate and show little sign above ground.

Disease - No rust reports in sentinel plots in the Lebanon area. Brown spot very prolific this season.

Weeds - Many weed escapes and resprays that failed leading right into new rains bringing yet another round of escapes in some cases with later germinators (nightshade, fall panicum, and large crabgrass).

Del Voight, dgv1@psu.edu
Lebanon County

Central

Within the last two weeks our area has received between 2 and 8 inches of rain depending on your location. This rain came at an extremely critical time for the corn crop which had been struggling from drought conditions. Some areas seem to have recovered completely and other fields are still uneven and look stressed, but continue to grow. On the average our corn had lost yield but still has the potential for an average crop. Weed control or lack of it has had a tremendous impact on how the corn looks. Late post emergent applications and rescue applications did not seem to completely control the grass weeds. Most of the grasses were stunted and suppressed but not killed. Many nitrogen sidedress applications were done under hot dry conditions, so the amount of this nitrogen taken in by the plants will be in question.

Alfalfa growth was also slowed by the dry conditions. Recently harvested fields seem to be growing extremely fast and should be ready to cut very soon. Potato leafhopper numbers rose rapidly and most growers applied insecticide either to the second or third cutting. Grass hay fields have had their growth reduced significantly. Prior to the recent rains, they basically showed no growth. Some fields have 40 plus days since last cutting and are just getting close to being tall enough to cut.

Soybeans have finally hit their growth spurt. In the last 2 days I have checked 3 farms with herbicide damage on their soybeans. The damage is very evident in the fields. One was from drift and the others were from sprayer tank contamination. Barley and wheat came off in good condition with good to excellent yields. Lots of high quality straw was also baled for the high priced straw market.

Craig Hostetter, gjh10@psu.edu
Juniata County

Northwest

Concern over dry conditions has softened with recent rains and has been replaced by increasing anxiety over the possibility of soybean rust appearing. Soybean fields scouted in Mercer County over the past two weeks have shown mild to moderate presence of Brown Spot and one field with scattered Phytophthora Root Rot. Soybean rust apathy is yielding to heightened grower awareness and interest in scouting. As bad as this new problem could become, the silver lining may be a more informed group of producers who will better understand a number of diseases and pests which have long had an impact on soybean production.

Potato Leafhopper populations are beginning to exceed economic thresholds at a time when weather conditions are limiting control strategies. Several farms have mentioned disappointing forage analysis of second cut forages.

Early planted corn is well into tassel.

Gary Micsky, gwm6@psu.edu
Mercer County