More soybean aphid in 2003 |
Soybean aphid numbers are greater this year than in 2002. Aphids colonized fields earlier (first week of June) than we have noted in the past. Winged aphids appeared to come out of buckthorn into soybean for at least four weeks, so the colonization period was extended throughout June. We recently noted fields in southern Michigan that seem to have been colonized very recently - early July, and I wonder if this is secondary colonization - i.e. colonization by winged aphids produced on soybean itself. As far as numbers of aphids, research fields on the MSU campus have 20 to 30 percent of plants infested. Infestation consists mostly of a few aphids per plant, although we have found occasional plants with over 100 aphids. Elsewhere, there are reports of aphids in fields across Michigan, the Midwest and Ontario. In most cases, people report more aphids this season than last. Dr. Ron Hammond from Ohio State University found few aphids in 2002, but this year he already reports fields in northern Ohio with 50 percent of plants infested. Bottom line, soybean aphids are widespread and the numbers are greater than last year (but still lower than 2001!). If you have been in soybean field, you have probably noticed fewer ladybugs this year than in years past. However, predation of aphid is occurring in the field. As part of our field research, we enclosed soybean plants in predator-proof screen cages three weeks ago. Since then, aphid numbers in the cage built up dramatically; this week we counted up to 6,000 aphids on a single plant. Clearly there are beneficial insects reducing soybean aphid population growth. To scout for soybean aphids, concentrate on the upper trifoliates, since most aphids are currently concentrated on the growing point. Infestations of just a few aphids are often nestled in the hairs on the emerging trifoliate. However, we noticed that on heavily infested plants, aphids move down the stem on to lower leaves. Infestations close to the suggested threshold (discussed later in the article) should be easy to see, since many plants in the field will be infested. The window for scouting is now through early August. Spraying after flowering did not increase yield in research plots. Based on several years of plot data, researchers in the Midwest set a tentative action threshold of 250-300 aphids per plant (note - finding a couple heavily infested plants in the field is not threshold - we are talking about a broader infestation of most plants in the field). This threshold is comparable to a leaflet rating of 2 [11 to 25 aphids per leaflet] in V5-V6 soybeans. The leaflet rating was published in the MSU soybean aphid bulletin last year - we hoped to provide an alternative to whole-plant aphid counts, which seems cumbersome. However, at this point with low aphid numbers, the aphids are grouped up on the upper trifoliates, and the lower leaflets are clean. If populations increase, I suspect aphids will move down the plant, and by the time we reached 250-300 per plant, we may be able to sample leaflets and reach a similar conclusion as sampling whole plants. In any case, the important thing is to get out and walk fields, and see how many aphids you have. As far as insecticides for soybean aphid control, note the list in MSU Bulletin E1582. In past trials, Asana, Lorsban and Warrior were the best aphid treatments. Dimethoate was a stinker in many trials. There is continued talk of using a 'preventative' spray before threshold - i.e. spraying at the first sign of aphids in the field, rather than waiting to see if aphids reach a threshold. This is not recommended, and there is no evidence that a preventative spray is useful in keeping aphid populations low. In fact, spraying too early may simply kill predators that are colonizing the field, enabling aphids to build up where otherwise biological control may have done the job. If you have anything interesting to report about soybean aphid, please email or call! You can reach me at: difonzo@msu.edu (note - the MSU email system is undergoing changes and has been malfunctioning) or 517-353-5328 for voicemail. |
Corn blotch leafminer appears again |
Corn blotch leafminer (CBL) has been found in a few fields in central Michigan. Over the last several seasons, this uncommon pest was reported in large numbers in fields in the western part of the state, near Grand Rapids. The adult leafminer is a tiny fly, which lays eggs on the corn leaf. The larvae hatch and tunnel into leaves, feeding (mining) within the leaf itself. The mines are transparent and grow in size, as the larvae get bigger. In heavily infested fields, the corn leaves appear to be white from all of the mining activity. For those of you who work with beets, the damage is similar to that from spinach leafminer. There is little research done on this pest, because
economic problems are rare. Yield loss is not well defined, and
there are no thresholds. The University of Nebraska has a short
web-based bulletin on CBL, which is one of the few information sources
on this insect, at: This bulletin uses loss from hail damaged to estimate loss from CBL. With 50 percent leaf loss (from mines in this case), only a 2 percent yield loss is expected in 7-leaf corn, and a 6 percent loss in 10-leaf corn. However, yield loss estimates are not really helpful to make a control decision. Larvae are protected within the mine from insecticide sprays - therefore spraying is not recommended for this pest. The good news is as corn matures, the leaf surface toughens and plant injury from CBL is less. |
When is corn grain yield determined? |
At what point in the growing season is corn grain yield determined? Well, of course it involves the continuous interaction of genetic, climatic, soil, plant pest and nutrient factors present for a specific growing season. However, from a crop management standpoint, it is helpful to characterize the most critical stages of development in the life of a corn plant with respect to determining final grain yield. Following are four critical stages in the development of a corn plant that are fundamental to determining corn grain yield. The first of these critical stages is emergence. Corn does not have the ability to compensate for poor stands compared to other crops such as soybean. Establishing a uniform, optimum stand is the first step in developing corn grain yield potential. Studies on the genetic evolution of corn indicate that modern hybrids tolerate field stress associated with higher plant populations better than their earlier genetic predecessors. Growers should continually evaluate the carrying capacity of their fields by putting in a few strip trials to determine the optimum plant population for each field. Keep in mind that as corn genetics continue to evolve, you will likely need to continually adjust your planting population upward to find that optimum plant population for each field. The second critical growth stage is when the plant determines the number of kernel rows and the number of potential kernels (ovules) per row. This is primarily determined during the rapid phase of corn vegetative growth, which generally occurs in early to mid-July in Michigan. The number of kernel rows per ear is heavily influenced by genetics and is generally determined by growth stage V12, which corresponds to the 12 leaf collar stage. The number of potential kernels per row is being determined at V12 and is usually completed a week to ten days prior to silking (V17). The number of potential kernels per row is strongly influenced by field conditions. Managing corn to reduce environmental, pest, moisture and nutrient stress during this time will maximize the potential number of harvestable kernels. Follow a plan to ensure adequate nutrient levels and minimize stress from pests such as weeds and insects during this critical period to establish the potential for high yield. The third critical stage is pollination. Successful pollination is required to convert potential kernel numbers to actual developing kernels. Pollination occurs when a pollen grain is shed from the tassel, lands on an emerged silk, grows down the length of the silk, and successfully fertilizes the ovule. It generally takes 2 to 3 days for all the silks on an ear to be exposed and pollinated. Pollen shed generally occurs in the late mornings and early evenings and the pollen shed period typically lasts from 1 to 2 weeks. From a management perspective, there is not a lot that can be done to ensure good pollination since it is highly dependent upon the weather. Droughty conditions can de-synchronize pollen shed and silk emergence and also can desiccate silks and pollen grains. This results in barren ears or in short ears with barren tips. Insect pests such as adult corn rootworm beetles can feed on emerging silks and reduce pollination and, therefore, should be scouted during silk emergence. Finally, because the tassel and all leaves are completely exposed, the plant is especially vulnerable to hail damage at this stage. The final critical growth stage for determining corn yield is the grain fill or kernel development period. The grain fill period, which begins at pollination and ends at kernel black-layer formation generally takes from 60 to 70 days (855 to 1200 GDD) for Michigan conditions depending upon climate, planting date and hybrid relative maturity. Both kernel number and the size and weight of harvested kernels are determined at this time. Stress on the corn plant can affect final yield by reducing either of these factors. Although field and machinery conditions can still influence final harvestable yield, the corn plant photosynthetic factory has completed its work at the kernel black-layer formation stage of development. For more information on corn plant development, see Iowa State University Special Report No. 48, How a Corn Plant Develops. This publication can be accessed on the Internet at: http://maize.agron.iastate.edu/corngrows.html |
Is the EQIP Program beneficial to you? |
Of course, only you can answer this question, but here is some information that may be useful as you consider it. The Environmental Quality Incentives Program (EQIP) is a voluntary federal program administered by USDA NRCS that supports the use of structural and land management practices by growers on their land with the aim to address environmental and key resource concerns and to improve the farm's economic outlook at the same time. For plant production, their agrichemical containment facility "structural practice" has been beneficial to many growers interested in minimizing problems in storing their pesticides and fertilizers. Other structural practices, such as hedgerow planting, field borders and filter strips, also have promise from a crop and pest management perspective, but they have been less utilized. For these practices, the program provides payments at a specific percent of the cost of implementing the practice. Other practices called land management practices that need to be implemented yearly also seem well suited for use by plant-based agriculture. These include IPM, cover crops, nutrient management, residue management and strip cropping. The program provides incentive payments on a dollar per acre rate for a set number of years (most commonly for three years) and with a possible total acreage limit for any one practice. Identifying practices that you want to try and suits your needs is of course fundamentally important, but also remember that the practices must also address one or more identified resource concerns such as groundwater protection (Do you have leachable soils?) and riparian protection (Do you have potential for agricultural water runoff?). Local district conservationists (they are your local representatives of USDA NRCS) may be especially helpful in this area. They are well aware of their district's resource concerns and can help identify practices (structural and land management) that can aid your farm's economic outlook and address key resource concerns. They have access to information from many sources, like IPM information from MSU (http://www.ipm.msu.edu), and they often work with your local MSU Extension agent. To raise your application high on the priority list, it is wise to identify at least two resource concerns and identify a number of practices to address these concerns. Again, your district conservationist can be very helpful. In many cases, it is the combination of practices that can really help: payments increase for you and more practices are implemented to address resource concerns and better your farm's economic outlook. For example, it may be very appropriate to link up IPM, cover crop and residue management incentive payments to address a couple of resource concerns related to water. If this sounds interesting, the article by C. Coulon in this newsletter provides specific details on the application procedure and obligations of the grower. She also provides information on how to contact your local district conservationist. The first deadline for new 2003 applications is July 11 with additional sign up opportunities on August 1 and August 22. You should visit your district conservationist as far ahead of the deadline as possible. |
The 2003 Environmental Quality Incentives Program in Michigan |
The Environmental Quality Incentives Program (EQIP), originally revealed in the 1996 Farm Bill, was re-authorized in the 2002 Farm Bill. The program, designed to assist agricultural producers with both the technical aspects of conservation planning and the financial aspects of conservation practice implementation, has proven popular with agricultural producers. Changes in the 2002 Farm Bill expanded the scope of EQIP and removed some provisions existing in the previous legislation. Several significant changes to EQIP occurred in the 2002 Farm Bill. The removal of geographic Conservation Priority Areas and the removal of an annual payment limitation increased program flexibility. Contract lengths changed from 5 to 10 years to 1 to 10 years, with payments available during the first year. Total program payments increased from $50,000 per individual or entity to $450,000. Authorized funding increased from 1.3 billion nationally for the 1996-2001 Farm Bill time period to 4.6 billion nationally for 2002-2007. A provision was included for the development of a Conservation Innovation Grants program, which would stimulate innovative approaches environmental enhancement and protection through leveraging of federal funds. Although authorized, this grant program is not yet available. Optimizing environmental benefits provides the foundation for EQIP. Conservation practices that address priority resource concerns are ranked to establish the applications that have the greatest environmental benefit. The following priority resource concerns have been established in Michigan based on county resource assessments, statutory requirements in EQIP to assist landowners address federal, state and local laws, and established national priorities: threatened, endangered or special concern species systems, comprehensive nutrient management plan systems, integrated wildlife management systems, riparian corridor management systems, groundwater resource protection systems, air quality protection systems, integrated conservation cropping systems, animal production management systems, and forestry systems. Michigan producers interested in applying for EQIP fill out a pre-application tool to determine their eligibility for EQIP. This form asks producers if they wish to address any of the nine priority resource concerns identified for Michigan. If the answer is yes to this question and to all of the other criteria on the form, they are eligible to apply for EQIP. The producer would then begin developing a conservation plan outlining conservation practices to address their resource concerns. A list of cost-effective EQIP eligible conservation practices as well as cost-share and incentive payment rates for these practices has been developed for 2003 EQIP applications. Once conservation practices are selected, a selection worksheet is used to prioritize applications. Applications are given a high, medium or low priority based on the priority resource concerns addressed. Addressing multiple priority resource concerns increases a producer's chance of being selected for EQIP funding. NRCS has made the application process as transparent as possible by posting selection worksheets (also referred to as ranking criteria), conservation practices eligible for funding and cost-share/incentive payment rates on the Michigan NRCS website. A step-by-step guide on how to apply for EQIP, a pre-application tool and application forms are also available to view and download from the website. NRCS staff in county USDA Service Centers, conservation district staff, and technical service providers can assist with applying for EQIP and conservation plan development. For more information on EQIP visit the Michigan
NRCS website at: An NRCS staff and office directory is available
on the Michigan NRCS website at: A note on pest management and
EQIP § $3/acre for 3 years for field crops (not to exceed 500 acres/yr) § $8/acre for 3 years for vegetable crops (not to exceed 100 acres/yr) § $20/acre for 3 years for fruit/nursery/Christmas trees (not to exceed 200 acres/yr) |
Regional reports |
Weather news |
On Thursday morning (July 10), a complex weather system atypical for the mid-summer months was approaching Michigan from the southwest. This system will bring widespread rainfall to much of the state before the precipitation tapers off late Thursday evening or Friday morning. Rainfall totals are expected to be heaviest in southern sections of the state (some 1- to 2-inch totals are possible) decreasing to scattered 0.25-inch totals in northern portions of the Upper Peninsula. Severe thunderstorms are a possibility in southern sections of the Lower Peninsula during the afternoon and early evening hours Thursday. Looking ahead, while drier weather is expected Friday, relatively cool air aloft will lead to the continuing possibility of a scattered or isolated shower each day into the weekend. Temperatures will fall back to below normal levels by Friday, with highs ranging from the low 60's north to low 70's south, and lows generally in the 50's. A gradual warmup is expected by late in the weekend into early next week, with another weather system bringing the chance for more significant rainfall Monday or Tuesday of next week. In the medium-range time frame, the NOAA 6-10 and 8-14 day outlooks for July 11-15 and 17-23, respectively, both call for a return of upper air ridging across central North America and above normal temperatures for much of the Midwest region including Michigan. Precipitation totals during both time frames are forecast to range from near normal in northern sections of the state to below normal in the south. Due to differences in the model guidance used in the development of the outlook, forecaster confidence is considered lower than usual for the season. |