General Comments: Alfalfa plants have broken winter dormancy
and the new shoots are growing. Alfalfa weevil eggs that were in the stem of last year's
growth will begin to hatch between early to mid-April. These eggs may result in an early
population of the pest, but under most conditions they are insignificant and only
represent about 10% of the total alfalfa weevil population. Alfalfa plants will typically
outgrow this injury. The population of economic significance results from eggs laid in the
spring by overwintering adults. These adults move into hay fields containing alfalfa as
soon as the plants begin to grow and lay their eggs in the stems of plants. The weevil
eggs hatch between mid-April and early-May. Larvae hatching from these eggs reach maturity
in approximately three weeks, normally from late-May to early-June. Injury symptoms are
usually most evident during mid- to late-May. Once the larvae pupate, they are done
feeding for the year and scouting efforts can cease. For this reason, scouting for this
pest only needs to occur during the first growth period (first cutting) of alfalfa.
However, in fields where high numbers of weevil are present at cutting, the stubble should
be checked to assure that regrowth is not being prevented by larvae feeding on the new
shoots. At spring green-up fields should be checked for stand density and a determination made concerning the need to rotate to another crop. Equipment needed:
Additional Information: When scouting, select several fields in your area with the following characteristics to determine when to begin scouting all fields in the area:
Begin scouting all fields once evidence of alfalfa weevil injury is observed. Stop scouting when the majority of alfalfa weevil larvae have pupated. Monitoring Procedures: Begin scouting when noticeable feeding injury to the plant tips is observed in alfalfa or when 300 degree days (base threshold of development = 48oF) have accumulated since January 1. This will typically occur between May 1 and May 15 in most years and at most locations in the state. To sample a field, carry a bucket (a 2- or
3-gallon size plastic bucket will do fine) and walk through the field in either a
"W" or zig-zag" pattern. After you have collected 30 stems in the bucket, separate them into 3 to 4 small bundles and beat each bundle 10 or 15 times against the inside of the bucket to dislodge the larvae from the stems. We are primarily interested in the large larvae (green in color and 1/4 inch long), since the big ones do the most feeding. In most cases only the large larvae are easily dislodged from the plant. Smaller larvae tend to hide in leaflet collars and are difficult to dislodge. Count all the larvae in the bucket, including the small cream-colored ones. Record this number on your field data sheet. Next, measure 10 of the stems to get an average height of the plants (in inches) in the field. Record the average height of the plants on your data sheet. Also, observe the stems and record the percentage with buds. The number of flower buds present will help you decide whether to spray or harvest the field if weevil larvae numbers are near the economic threshold and the field is near the harvesting stage of development. If the field is in full bud when the economic threshold is reached, early cutting is usually the best pest management alternative. See Table 17 for economic thresholds.
General Comments: Potato leafhopper adults migrate into Pennsylvania on storms that originate in the Gulf of Mexico. Therefore, the time of year when they begin to colonize alfalfa fields in the state varies up to six weeks. Because the exact time of migration into Pennsylvania is not 100% predictable, scouting for the pest should begin when the second and third growth of alfalfa reaches 2 to 4 inches in height. New introductions of leafhopper into a field can occur after each spring rainstorm that was generated in the Gulf of Mexico or that moves up the Atlantic coast. During the third crop, most movement into a field is from surrounding fields. Watch new growth for an influx of leafhoppers after a nearby alfalfa field has been cut.
Monitoring Procedures: There are two common methods of scouting for potato leafhopper in alfalfa fields: fixed and sequential sampling. Both procedures are discussed below.
General Comments: The majority of soybean varieties planted in Pennsylvania have an indeterminant growth pattern. South of Pennsylvania, determinant varieties become more common. Determinant varieties stop vegetative growth once reproduction begins; indeterminant types continue to add vegetation and additional reproductive structures after the first flowers are set. Because of this continuation in growth, indeterminant varieties can recover from stresses better than determinant soybeans. Therefore, economic thresholds for insects and diseases are higher for indeterminant soybean varieties. Optimal final soybean populations are 150,000 plants per acre for full-season beans and 200,000 plants per acre for double crop beans. Seeding rates can be increased by 5 to 15% depending on planting conditions. Soybeans have a great capacity to compensate for missing plants. They compensate for missing plants by developing more branches and podding more heavily. Potential soybean yield will not be reduced by a reduced population, but pod height will be lower, which can increase harvest loss. Population reductions can also lead to a reduced ability to compete with weeds, leading to increased weed competition and lower yields. Insects that attack soybeans before the first trifoliate leaf has emerged are defined as early season in this manual. In Pennsylvania, insect pests that would cause damage during this time are seed corn maggot, wireworm, bean leaf beetle, potato leafhopper and thrips. Of these, the seed corn maggot is the most common insect causing economic injury to soybeans. Another pest, that is not an insect but a mollusk, is slugs. This pest is growing in importance as more soybeans are planted in the state, particularly when soybeans are planted no-till during late May. Three plant diseases, phythophthora, pythium, and rhyzoctonia are commonly observed during this period. During the period from planting to the first trifoliate leaf, soybeans are very susceptible to injury from insect feeding. If a plant is cut-off below the cotelydons, it cannot recover and will die. Significant leaf area removal on these small plants can lead to desiccation and the death of young seedlings. Therefore, it is important to protect young seedlings from injury by insects and disease. Equipment Needed:
Additional Information: A seed treatment at planting can reduce the likelihood of losses from insects and seedling blights. However, it is important to read the seed treatment label to prevent killing the bacteria in soybean inoculant. When growing conditions are good, the germination process will have begun and the young seedlings should be emerging from the soil. However, if soil conditions are dry and/or temperatures are cool, germination and plant emergence will be delayed. Delays in emergence caused by wet and cool conditions can allow seed corn maggot, slugs, and seedling blights to consume the developing seedlings. Monitoring Procedures: Planting to emergence Two weeks after planting, begin monitoring soybean fields for emergence, insects, weeds, and diseases. See the section on how to conduct a spring weed survey for specific weed monitoring procedures. Measure off 10 feet of row at 5 random locations in the field. Count the number of emerged plants and look for any evidence of injury from insects or disease. After counting the emerged plants, dig into the soil and check for unemerged seeds to see if they have germinated and are still viable. Keep track of the number of plants that show evidence of insect feeding or disease, as well as those that are healthy. Continue monitoring emergence on a weekly basis until 100% of the viable seed has emerged. If significant stand reductions occur because of insects and diseases, or because of other production problems, then replanting may be necessary. However, in most cases the costs of replanting are greater than the loss from stand reductions. If you have questions about replanting, you should contact a crop management professional. There is no rescue treatment for insects and diseases that attack during this time. In no-till fields, if slugs are feeding down in the planter slit, then a rescue treatment using a metaldehyde bait can prevent further stand losses. Emergence to the First Trifoliate Leaf During this time period the best approach for scouting soybeans is to examine 10 feet of row at five random locations in the field. On each plant look for visual signs of leaf feeding or disease development. If insect feeding is evident, determine the percentage of plants affected, the degree of defoliation on each plant (percent leaf area removed) or the number of plants cut. (See defoliation chart in reference section of this manual.) If present, count the number of insects on each plant and identify the species. If bean leaf beetle is the causal agent, estimate the percentage of plants cut and size of gaps in each row. With slugs, estimate the number of plants missing and/or the percentage of leaf area removed. For thrips, turn the trifoliate leaf upside down and count the number of thrips on the underside of the leaf. See the resource material "Pests of Soybeans I" and "Marsh Slugs" for pictures of plant injury symptoms. Compare your observations with economic thresholds in Table 19. Rescout the field every 7 to 10 days. While scouting for insects a casual observation for diseases also can be conducted. If you cannot sight identify a disease send it to the Penn State Plant Disease Laboratory.
General Comments: Mid-season defines the period in crop growth from the second trifoliate (V3) to full bloom (R2). Late season is defined as the period from R2 to R8. During this period much of the vegetative growth occurs and the first flowers appear on the plant. Pods have not yet begun to form. Because plants are actively adding new vegetation and flowers, the plant can tolerate a high level of defoliation without significant yield reduction. When defoliation does occur, new leaf growth is stimulated by the additional light that reaches the lower leaves of the plant. It has been shown that some defoliation of the upper leaves can lead to increased yield by the plant overcompensating for injury. Arthropod pests that attack the plant during this period include the green cloverworm, bean leaf beetle, potato leafhopper, grasshoppers, Japanese beetle, Mexican bean beetle, thrips, and two-spotted spider mites. These pests feed either on leaf tissue or the contents of individual cells. Diseases that can be observed during this period include brown spot, phytophthora, white mold, pod and stem blight, brown stem rot, and anthracnose. Additional Information: Two-spotted spider mite - soybeans injured by this pest have leaves with a yellow or brown appearance. On close observation the leaves appear stippled. If injury is severe, the plants will turn brown and die. Usually mite infestations begin along the margins of a field near grassy areas. Potato leafhopper - soybeans injured by this pest turn yellow at the leaf tips and the new leaves appear crinkled or cupped. From a distance the injury may appear similar to Banvel injury.
Equipment Needed:
Monitoring Procedures: Monitoring during this time period is based on visual assessment of damage and insect numbers. The best tool to help assess insect numbers is a shake cloth, also known as a beat cloth. A shake cloth is a white muslin sheet about three feet long and 30 inches wide. This cloth is laid between two rows of soybeans. In 15 inch or narrower rows this may require knocking down a row or two of soybeans so that the cloth can be laid flat on the ground. After the cloth is in place, measure off a one foot long section of row on each side of the cloth. Beat the soybeans on the cloth for about 30 seconds. This should dislodge most insects, which will fall on the cloth. Count the number of each pest species found on the cloth. Also, note the type and degree of injury symptoms observed on the plants. Use the "Defoliation Chart" in the reference section to estimate the percentage of leaf area removed by insect feeding. Repeat this process at nine more locations in the field. After monitoring is complete, calculate the number of insects observed per plant and compare with economic thresholds (Table 19).
General Comments: Small grains or cereal crops follow the typical growth stages of grasses. The growth process can be broken down into four major periods:
Winter wheat, barley, and rye are planted in September and October in Pennsylvania. Spring oats are planted from late March to mid-April. The winter grains begin vegetative growth in the fall, but do not begin stem elongation and heading until the following spring. Spring oats complete their entire development during the year they are seeded. Of the major insect pests of small grains, aphids and Hessian fly attack in the fall. Aphids, true armyworm, cereal leaf beetle, and Hessian fly attack during spring and early summer. The significant diseases of small grains are powdery mildew, septoria, and leaf rust. Other common diseases include head scab, take-all, barley yellow dwarf virus, and soil-borne mosaic virus. Additional Information: None Equipment Needed:
Monitoring Procedures: The monitoring procedures in small grains vary depending on pest species, but in all cases, 20 plants should be examined at five random locations in the field. During periods when aphids are present look on the underside of leaves for colonies. Count the number of aphids per stem and record the information on a data form. Scouting for armyworm is similar, but armyworms tend to be nocturnal and are easier to see toward evening or on overcast days. Because of their nocturnal habit, injury symptoms will be seen when scouting during the day and few larvae will be found. When injury is observed, look deep in the small grain canopy and under debris on the soil surface for larvae. Count the number of larvae per foot of row and record the information. Scouting for cereal leaf beetle is the same as aphids, but count the number of eggs, larvae and adults on each stem and note the number of flag leaves with feeding damage. To scout for Hessian fly the best method is to look for brown puparia, commonly called "flaxseeds" between the leaves and stem of all tillers. Determine the percent of plants infested. Disease monitoring can be done while scouting for insects. Look for yellowing, reddish or purple discoloration, or dying leaves as evidence of disease. Plants with powdery mildew will have whitish mold on the lower leaves. Plants with leaf rust will have red pustules on the leaves. Note diseases and their intensity. When severe infections occur a fungicide application may be needed. It is important to prevent infection on the top two leaves since these leaves contribute most of the dry matter to the grain.
To practice IPM, a practitioner must know what management tactics are available and when they can be used. Management tactics can be broken into: 1) preventative methods and 2) remedial methods. Preventative methods are practices that when implemented make a field less attractive to migrating pests, prevent introduction of a pest, modify the field environment to discourage or reduce pest population growth, eliminate shelters for pests, eliminate reservoirs of pest populations, improve the crop's environment so it can compete better and tolerate more pests, break the pest's life cycle, avoid the pest, and improve the plant's genetics to tolerate or resist pest attack. Preventative methods, when properly implemented, are designed to maintain a pest's population below the economic threshold. Remedial methods are practices that are implemented once a pest's population has exceeded the economic threshold. Remedial methods can be cultural, chemical, or biological practices. Examples of cultural remedial methods used for weed management include: rotary hoeing, cultivation, clipping of forage seedings, and mowing of pastures. For insect management remedial methods may include the release of biological control agents, adjustment of harvest date and the use of properly timed insecticide applications. Examples of remedial methods for disease management include fungicide applications and mowing of forages. All the preventative and remedial management tactics available to field crop farmers are listed below. The combination of tactics selected by the farmer will depend on the complex of pests he or she needs to manage. Not all tactics are complementary. In some cases, a tactic that will help regulate the population of one pest may make the field susceptible to attack by another pest. To effectively implement an IPM program, a farmer or crop management professional must know which combination of tactics is best for the pest complex of concern. A good IPM practitioner should use all practices that are compatible with his/her farm's or client's resource base (labor, knowledge, equipment, land, capital, etc.). If a practice is not a viable economic alternative, then another practice should be substituted. No one will use all possible practices on their farm and they shouldn't try. The selection of practices used will depend on the key pests that need to be managed and the crop production system. To select practices, a farmer should first prioritize the relative importance of each pest. Management practices that help control the most important pest(s), that are compatible with his/her farming system, should first be selected and implemented. Next, management practices that will help control the pest(s) of second priority, that do not interfere with those used for the top priority pest(s), should be selected. Using this process, a set of management tactics can be selected that will help prevent most injury from the major pests of concern. Pests of lower priority can be dealt with on an as need basis. Weed Management Tactics Preventative or Cultural Methods
Remedial Methods (non-herbicide based)
Remedial Methods (herbicide based)
Insect Management Tactics Preventative Methods
Remedial Methods
Disease Management Tactics Preventative Methods
Remedial Methods
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Randomly
remove an entire stem from 30 locations at approximately equal intervals, in order to
obtain a good representative sample of the field. When collecting an alfalfa stem sample,
carefully cup your hand around the top of the stem before removing it. This will prevent
any larvae from dropping off that may have been on the stem. Now, remove the stem at
ground level and place it top first into the bucket. Repeat this procedure as you follow
your pattern across the field. 
Equipment needed:
Fields can be sampled any time of the day when the alfalfa is dry.
Avoid sampling in cold or windy weather and when the alfalfa is wet. Sample at five
selected sites in each field along the sampling path. 
Thrips - soybeans injured by thrips have
whitish areas along the leaf veins, and on close observation small black specks that are
their droppings. If injury is severe, the new leaves will be crinkled and somewhat
deformed. 
