| Soybean aphid update | At the risk of sounding like a broken record, aphids continue to increase dramatically in certain parts of the state, especially in areas lacking rainfall. For example, research plots at the Bean and Beet Farm in Saginaw County increased from 10 to 20 per plant on July 6, to hundreds per plant (over the 250 threshold) on July 13. In heavily infested areas, honeydew is beginning to accumulate on leaves. Cruiser treated plots, as well as untreated plots, are over threshold, although the Cruiser treated plants are a bit taller than the untreated plants. In fields that lacked aphids, we are noticing numerous winged migrants and tiny new babies. Under favorable conditions, these aphids will increase rapidly. There isn’t much more to say that hasn’t been said. Remember it is still relatively early in the season, and we have a good four to five more weeks of aphid reproduction to contend with. Continue to scout fields, and if treatment is needed, blast that spray down into the canopy! |
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| Aphid sucker is in business | The year 2005 was predicted to be a heavy year for soybean aphids. That prediction came from Dr. Dave Voegtlin, an entomologist with the Illinois Natural History Survey. Dr. Voegtlin runs a series of suction traps across Illinois to sample migrant aphids flying in the landscape. Over the past four years, counts of the soybean aphid in the Illinois suction traps in the fall have reflected the observed population of soybean aphids in the field the following season. This data is at: Dr. Voegtlin’s findings of heavy movement in the fall of 2004 were backed up by buckthorn sampling in late fall, which showed numerous eggs. This spring, we experienced heavy colonization of SBA moving from buckthorn to soybeans – so the prediction was correct for 2005. Suction traps are one of the most unbiased sampling methods for aphids. They do not rely on aphid behavior to catch the critters (like, for example, yellow sticky traps). Instead, they suck in a certain amount of air in a given amount of time; the aphids in that air are captured in a bottle at the base of the trap. Trap catches can be directly compared from place-to-place and time-to-time. The traps are relatively easy to operate – they simply plug into a power source and run continuously, with the sampling bottle changed each week. The real challenge comes in sorting and identifying the trap catch. Based on the success of the Illinois state network, this summer the field crop entomologists in several Midwest states expanded the network to a regional level to monitor movement of the soybean aphid and other agriculturally important aphids (including species that transmit viruses in vegetable crops). The traps were built by the University of Illinois and distributed to surrounding states by Dr. Voegtlin. The following states are now running multiple traps for the Network: Illinois, Indiana, Iowa, Kentucky, Michigan, Minnesota and Wisconsin. In Michigan, the traps are located at the Kellogg Biological Station, at the MSU Entomology farm on campus and at the MSU Bean and Beet Research Farm. Each state is responsible for maintaining the traps, changing the sample bottle and sending weekly samples in for sorting and identification to the Voegtlin lab at the Illinois Natural History Survey. In the next edition of the Field Crop CAT Alert, I will provide several weeks worth of trapping numbers and identifications from Dr. Voegtlin. These numbers are also being provided to cooperating farm locations, Extension educators and MABA, so you hear about the trapping results from several sources. |
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| Predators suppress soybean aphid in some Michigan fields
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Depending on where you farm in Michigan, you may have observed soybean aphid numbers increasing, decreasing or remaining about steady. What factors are responsible for these fluctuations? As part of a multi-state study of soybean aphid IPM, we are sampling soybean aphid and its natural enemies in four fields in Kalamazoo, Saginaw and Gratiot counties. On June 28 we observed aphid populations reaching as high as 173 per plant in one Kalamazoo County field. However, the following week (July 5) populations in the same field declined to less than 70 per plant. To understand if predators are the cause of soybean aphid decline, we compared aphid populations on plants open to predators versus plants caged to prevent predators from eating aphids. On the caged plants, aphid populations increased from 10 aphids per plant to 784 per plant in two weeks (Figure 1). While on the open plants, predators maintained aphid populations below 100 per plant over the same two-week period. The most common predators collected in the Kalamazoo County field were the seven-spot lady beetle, multi-colored Asian lady beetle and minute pirate bug. This field averaged 0.6 predators per plant on June 28. Despite what seems like a small number of predators per plant, natural enemies are impacting aphid populations in this field. By comparing aphid populations in cages excluding predators with plants open to predation, we have shown that the decline in aphid numbers from June 28 to July 5 is due to predators consuming soybean aphid. The caged and open plants were in the same field and subjected to the same environmental conditions, ruling out rainfall, weed control or other cultural practices as the cause of aphid reduction. Therefore, if you are seeing aphid populations in your field level off or begin to decline, you may want to wait to spray to see if predators can maintain this pest below the 250 aphids per plant threshold. |
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| Asian soybean rust sentinel plot scouting report for July 7 to July 13
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There were 19 reports filed from the 20 sentinel plots during the reporting week. Following is a compilation of the reports. Growth stage: Six plots=R1, 10 plots=R2, 1 plot=R3, 1 plot=R4. Plant height: Ranged form 13 to 26 inches with the majority between 16 and 20 inches. Degree of canopy closure: Ranged from 50 to 100 percent and averaged 85 percent. Soybean diseases present: Low levels of brown spot (13 plots), low levels of bacterial blight (7 plots), low level of downy mildew (1 plot) and low levels of phytophthora stem canker (2 plots). Insects present: Soybean aphid remains at low levels in 16 of the plots. One plot recorded 250+ aphids, and two of the fields containing sentinel plots have been sprayed for soybean aphids. Comments: Drought seems to be having a significant impact on soybean plant growth. In one sentinel plot within an irrigated field, canopy cover was 100 percent where water reached the plants and only 75 percent where water did not reach. One soybean sample from a sentinel plot was submitted to MSU Diagnostic Services and tested negative (using real-time PCR) for soybean rust. The symptoms – small chlorotic flecks – were caused by downy mildew (Peronospora manshurica). Under high relative humidity grayish tufts of sporangiophores may be visible on the lower surface of lesions. Older lesions that are necrotic do not have these tufts. The sporangiophores are best seen with a hand lens or a dissecting microscope. According to the University of Wisconsin (http://www.plantpath.wisc.edu/soyhealth/minordiseases/downy.htm), downy mildew commonly occurs wherever soybeans are grown but rarely causes yield loss. MSU Diagnostic Services reports the following pests and problems found on field crop samples submitted in the last week: Soybean – Manganese deficiency; Downy mildew (two samples) Sugar beet – Cercospora leaf spot Wheat – Take-all No new soybean rust detections have been made on soybeans in the last week. The USDA soybean rust web site (http://www.sbrusa.net/) forecast dated July 13 states the following: “The soybean rust model indicates that light deposition of inoculum is possible over eastern Ohio, and extreme western Pennsylvania for the next two days. Greater deposition is indicated over Alabama, Georgia, South Carolina, North Carolina, eastern Tennessee and eastern Kentucky, Virginia, West Virginia from now until the end of the week. Infections in new deposition areas will not be observable for approximately two weeks, assuming favorable weather conditions.” Check the web site at: http://www.sbrusa.net/ daily for changing forecasts and predictions. |
| Fungicide precautions during stress periods | All pesticides can be toxic to plants if used inappropriately. This is known as phytotoxicity. In most cases, damage results from improper application or from pesticide drift from applications to neighboring crops. Incomplete cleaning of spray equipment can also damage nontarget plants from application of residues. Common symptoms of pesticide injury include: leaf, flower, ear and pod damage such as burning (especially at the leaf tips and margins), distortion, chlorosis (yellowing) and necrosis (especially between leaf veins). The type and severity of symptoms are normally dependent on the type and the concentration of pesticide. In many crops, damage may appear in patterns associated with application of the chemical or where there are stressful conditions such as localized drought. One of the most common environmental conditions that produce physiological damage in plants is temperature. Extremes of temperature can cause severe injury to plants and often results in death. Many agricultural crop plants exposed to high temperature (greater than 85°F) suffer excessive water loss through increased transpiration rates causing wilt, heat stress and sometimes sun scald on parts of the plant directly exposed to the sun. Stomata close and limit evapotranspiration resulting in stress damage, which is a result of production of secondary metabolites within cells. In many crops, heat stress is intensified by high humidity and dry soil. In addition, low temperatures can cause injury to plants. Cells close to the plant surface separate from core tissue giving the affected tissue a silvery appearance that eventually turns black or ruptures. These ruptures from both high and low temperature injury are entry sites for secondary organisms such as fungi and bacteria. Agrochemical companies have invested much effort and research into the potential for phytotoxicity resulting from application of pesticides under a range of conditions. Optimization of formulations of pesticides to promote maximum efficacy and minimum phytotoxicity is important. Often it is not the fungicide active ingredient that causes the damage but a solvent required to dissolve or suspend the active ingredient in solution that is the damaging component. The fungicide group known as the triazoles has been associated with crop damage for many years in various crops e.g. Tilt (propiconazole), Folicur (tebuconazole) and Domark (tetraconazole). These products have not been reported so far to cause damage in soybeans, however if applied during hot weather (greater than 80°F), the risk of damage being expressed are amplified. As little work has been completed on fungicide applications to soybeans, it would be prudent to avoid applications when temperatures exceed about 80°F, especially if the adjuvants that are recommended to promote coverage are used. Currently we are warning sugar beet growers not to apply EC formulations of fungicides when temperatures exceed 80°F and to avoid if possible mixing ECs together. Generally, to avoid damage to the crop, fungicides should not be applied when temperatures exceed 80°F or when stomata are closed during the middle of the day. For best effect, fungicides should be applied in the morning before wind and temperature increase, or similarly if applying by ground rig during the evening. Dew on plants can aid in redistribution of the fungicide and can also reduce toxicity by preventing localized concentration accumulations. BASF recently produced a document on adjuvant use with fungicides to be applied to soybeans. They have kindly allowed MSU to adapt this document for growers largely unfamiliar with fungicides. Currently, BASF has large research trials containing over 50 leading soybean varieties that are being screened for triazole sensitivity. Preliminary results from these trials confirm results from Brazil, that some soybean varieties grown under hot and dry conditions or other plant stresses may exhibit a crop response to some triazole fungicides. It was also observed that more aggressive spray adjuvants may increase potential crop response. The “response” that BASF refer to here is crop injury. The key points from their document are as follows. Standard recommendation § Refer to and follow label directions for adjuvants to be used with triazole containing fungicides. § Use the lowest labeled rate of adjuvants when tank-mixing with triazole containing fungicides. § Under environments of crop stress adjuvants may increase potential crop response. If the soybeans are under stress, do not use crop oil concentrate adjuvants. § In Brazil, triazole injury to soybeans typically causes no yield reduction. § Soybean injury to triazoles can take two to three weeks to be fully expressed and may not show any response for the first 10 days. Triazole injury symptoms are expressed as interveinal chlorosis or blotching, typically on just a few soybean leaves. § Injury symptoms are present only on the leaves on the top of the plant at the time of application. The triazole is not translocated to new soybeans leaves emerging after application. Therefore new growth after application does not express the symptoms. § Crop response is dependent on both soybean variety and environmental conditions. § Certain soybean varieties are more sensitive than others. In Brazil, the majority of the soybeans do not show sensitivity to triazoles. A small percentage can be sensitive at all times, while the remaining varieties show some sensitivity only when grown under stress conditions (usually hot and dry), for some triazoles. § Triazoles vary in their potential for crop response. § Tankmixing triazole containing fungicides with foliar fertilizers or insecticides may increase the potential or intensity of crop response. This is most likely to occur under crop stress conditions or on sensitive varieties. |
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| The Michigan Senate slated to hold public hearings on additional water protection measures |
Senator Patty Birkholz (R) Saugatuck Township (Allegan County) announced on July 11 that the Michigan Natural Resources and Environmental Affairs Committee, which she chairs, will hold four public hearings across the state to collect input on potential additional water resource protection measures that the state may consider implementing. Discussions at these sessions may have implications for agricultural water usage such as irrigation, on-farm processing of fruits and vegetables, and livestock watering. Producers may want to be aware of these meetings so they have the opportunity to make comments on the importance of water usage to their operations and industry. A press release written by Senator Birkholz’s staff indicates that the committee is, “Interested in hearing from our citizens their ideas to help conserve our waters." Senator Birkholz said, "Legislation is in place to allow us to take additional steps to safeguard our waters while still preserving access to groundwater resources, but we need local input in order to decide what those steps will be. We anticipate hearing many recommendations that will help us manage our waters better for the future." The committee will be hearing from local community members and representatives of the environmental community at the following locations from 7:00 - 9:00 PM: Thursday, July 14 Monday, July 25 Tuesday, July 26 Friday, August 5 The press release forwarded by Senator Birkholz staff can be found at: |
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| Regional reports
1 – Southeast |
Weather Scattered and locally heavy thunderstorms have produced up to 1.7 inches of rain at one location and perhaps nothing two miles away. Light hail and high winds have also accompanied these local storms. The remnants of Hurricane Dennis have been providing the current spate of local showers this week. Commodity reports Corn is performing depending upon the field receiving any rain. Advanced fields are beginning to tassel, while other fields are waist high and have leaves rolling in the morning. First (over wintering) generation of European corn borers have thoroughly infested some cornfields. If the second and possibly third generations are similar, this could be the worst year since 1996 when farmers were spraying for the first generation. Generally cornfields are shorter than normal because of the lack of rain. Soybeans are still suffering from manganese deficiency, aphids, spider mites, cyst nematodes and root rots. Remarkably, soybeans can still be sprayed with conventional tractors and ground sprayers as weed sprays are finishing up as some soybeans are only about 12 inches tall. Advanced fields are at R3 stage with small pods emerging. Aphid populations have diminished since the highs of early June, and the predator populations have increased. Yesterday, one farmer reported 75 aphids per plant, while the plots show lower levels at present. Many farmers have sprayed for aphids, tank mixing with glyphosate or with manganese. We have had three “false alarms” of soybean rust, including one call from the Cincinnati area, which had heard that we had rust. Wheat harvest has been short and intense and is virtually complete with yields generally down 10 to 35 percent. One farmer with a five-year average yield of 90 bushels is only getting 80 this year. Yields and test weights are surprisingly good, 60 to 61 pound test weights, given all the hot weather. Farmers are baling straw as fast as possible. Miscellaneous |
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| 2 – Southwest | Weather Commodity reports In seed corn, detasseling operations are proceeding at top speed. St. Joseph County has been one of the areas blessed with thunderstorm rainfall, so there is some concern that wet fields may slow down this operation. There have been applications of fungicides going on fields to help protect plants from the onset of foliar diseases. Not much new insect activity going on at this point. Soybean aphids continue to be found at low to moderate levels in many fields. Relatively few fields have been treated so far. Most fields have between a half to one aphid per leaflet at this time (20 to 40 pre plant) with the majority of aphids lower in the canopy. Continue to monitor fields for this pest. Growth stage ranges from pre-R3 (initial pod set to R1 on all but the earliest planted fields). Beans are also being hit hard by drought stress in the western portion of the region. Plant height is 8 to 12 inches in many of the hardest hit areas. Crop yields will be significantly affected by the drought conditions in a wide area of the region. In alfalfa, the hot, dry conditions have led to a good opportunity for producers to harvest second cutting. Re-growth is being affected by dry conditions. Leafhopper numbers are variable, but warrant grower diligence in terms of scouting. Wheat harvest is well underway in the southwest region. The dry conditions kept the incidence of head scab low. Yields have been somewhat reduced by dry conditions early in the season limiting head size. In places where the crop was raised where there was adequate soil moisture early in the season, yields have been pretty good. Dry conditions have allowed most producers to bale nice bright straw this season. The early-planted potato crop is sizing tubers. Some fields have been affected by hail in St. Joseph County. Snap bean harvest is beginning. Crop growth and yield potential looks pretty good at this point. |
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| 3 – West Central | Weather Commodity reports Corn growth has progressed. Much of the crop is about to put out the last leaf before tassel emergence. Leaf rolling is prevalent in dry-land corn in the northern and western areas of the region and on the very sandy soils elsewhere. European corn borer moth numbers in pheromone traps are very low, as second generation has not yet emerged. Dry beans are growing rapidly under irrigation. Most of this crop is experiencing overall good growing conditions. In soybeans, soybean aphid has been observed generally below threshold. Second cutting alfalfa is complete. Potato leafhoppers are present in alfalfa fields and should continue to be monitored. |
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| 4 – Central | Weather Commodity reports Soybeans are flowering and doing very well. We are seeing weed escapes in the conventional beans. There are soybean aphids in nearly all fields however we have only observed one field that was at threshold. Fields need to be scouted regularly to monitor aphid populations. Wheat harvest is just getting under way. Early reports are that yields are average at best. Quality is average. There are no reports of serious disease problems at this time. Grain moisture has been a surprise being as dry as 11 percent. Harvest of second cutting alfalfa is well under way. Some farmers are done and are happy with yield and quality. Leafhopper populations are medium. Fields should be scouted for this pest. Dry beans are doing well with no unusual problems at this time. Barley and oats are beginning to turn. Some weed problems are showing up in the oats, which may cause some harvest problems. Sugar beet fields that have good stands look very good, while some fields are trying to catch up. |
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| 5 – Thumb | Weather Commodity reports Except for a few places that have early season water damage, the sugar beet crop looks very good. Cercospera leafspot has been confirmed in many areas, which is consistent with the BEETCAST leafspot prediction model. Watch http://www.michiganbeets.com/ for updates for your area. Bacterial leafspot is still present in some areas so be sure to scout carefully. Harvest of wheat is well under way in the Saginaw Valley with good yields. Vomitoxin levels of tested wheat have been low (under 1 ppm) in most samples. Grain moisture is low in many fields but high humidity is causing threshing to be more difficult. The corn crop is using lots of moisture due to large plant size and high temperatures. This may take some toll as soil moisture is depleted and rainfall is limited. Some leaf rolling is occurring. Pollination is occurring is some early fields. Most fields are near or just beginning tassel emergence. This crop has looked very good to this point, hopefully we won’t give up much yield potential due to these dry conditions at this critical development point. Some high populations of European corn borer have been reported. Soybeans are showing good growth and development in past two weeks. Many fields are now in the R3 growth stage with small pods developing. Some no-till fields have slowed growth recently but appear healthy. Soybean aphids have been found nearly everywhere. Some places have reached the threshold of 250 aphids per plant and have received an insecticide application. These little critters seem to love this hot, dry weather and are taking full advantage of it. The aphids are more variable this year than in the past. Populations change dramatically between fields and within fields. Dry bean fields are looking pretty good with growers carefully watching potato leafhopper populations. Early planted fields are filling rows and looking good. The wild card will be the amount of root disease and its effect. Many fields that had water injury have limited root systems that are very shallow in the soil. This makes them most susceptible to drought stress. |
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| 6 – Northern Lower Peninsula | Weather Commodity reports Wheat is drying down fast with the hot, dry weather. Test weights may suffer due to the lack of moisture during seed fill. Soybeans are short and suffering in the current weather pattern. Most fields have started flowering with plants only about eight inches tall. Dry beans have looked good until recently. Hot weather as flowers come on worries producers. Stands are great overall. First cutting of alfalfa is complete with some starting second cutting already. Lack of rain is making a short second cutting. Bugs are prevalent in most fields with some spraying already occurring. |
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| Heat and dryness continue | Upper air ridging and surface high pressure across the Great Lakes region has persisted for much of the past several weeks, leading to abnormally hot and dry weather in Michigan. Unfortunately for those areas in need of rain, this pattern is expected to continue for at least part of the next week. Seasonal precipitation deficits (since April 1) currently range from about two inches in east central sections of the state to more than eight inches in some spots across southwestern Lower Michigan. Normal rainfall for this time frame is generally in the 9.5- to 11.5-inch range from east to west across the state. In the short term forecast, the remnants of Hurricane Dennis will remain almost stationary across the Ohio Valley through early Saturday. As has been the case for much of the past few days, this ex-tropical system will continue to set off scattered showers and thunderstorms across sections of the state each through Saturday with best chances for rainfall during the afternoon and early evening hours and geographically across the southern few tiers of counties in Lower Michigan. Rainfall will likely remain widely scattered in terms of areal coverage with most totals less than 0.25 inches, although some 0.50- to 1.00-inch totals are possible in a few (very lucky) locations. Dry weather is expected over most areas of the state by late Saturday (July 16) continuing into Monday. A cool front will approach from the west in the late Monday to Tuesday time frame, bringing the next best chance for significant rainfall. Temperatures will remain at above normal levels for the next several days with daytime highs ranging from the upper 70s in northern lakeshore areas to mid to upper 80s elsewhere. Low temperatures will range from the upper 50s north to the upper 60s to near 70 south. The NOAA Climate Prediction Center 6-10 day (for July 19-23) and 8-14 day (covering July 21-27) outlooks both call for broad upper air ridging across western sections of the country with weak troughing across the east with a continuation of above normal temperatures during both forecast periods. Precipitation totals during the 6-10 day period are forecast to increase to a range from near normal in most areas of the state to above normal in the extreme southwestern Lower Peninsula. Near normal totals expected statewide during the 8-14 day period. |
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