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| Field Crop Advisory Team Alert newsletter | ||||
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| Vol. 22, No. 15, August 9, 2007 |
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In this issue Aphids increase Spider mite control Western bean cutworm distribution maps available Do I have enough soil moisture to make a crop? Soybean disease update and fungicide use 2007 soybean yield contest Development of drought conditions in Michigan Drought on-line resource now available Regional reports WeatherNext issue August 23 |
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| Aphids increase Quick take home messages
Michelle Roy, an entomologist with the Province, reports that 90 percent of the acres in southwestern Quebec have been treated this year. My theory is that winged aphids were picked up, circulated and rained out to the west. By Friday, August 3, I had numerous reports of areas over threshold, including fields in Ontario, New York state and Northern Ohio. In Michigan, isolated fields are reported over threshold or increasing dramatically in Sanilac County and in the Jackson area. Fields with symptoms of potassium deficiency appear to have higher aphid populations. Earlier stage (later planted) fields may also have higher numbers. The outbreak isn’t widespread yet. Aphid numbers differ dramatically from field to field, so scout to determine which if any fields have a problem. |
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| Spider mite control Unfortunately, with the dry conditions mites are more common than aphids. Many are spraying in the southern tier of counties, and I’ve had a bunch of reports of mite populations returning after treatment. Several things may be happening:
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| Western bean cutworm distribution maps available Trap captures for 2007 are now posted on the western bean cutworm monitoring site at http://www.ent.iastate.edu/trap/westernbeancutworm/. There is a map of trap locations by county, plus several maps showing cumulative captures over time. This season moths were trapped in six counties in Southern and Central Michigan: Cass, Van Buren, Allegan, Ingham, Lenawee and Monroe. The hot spot was Cass County with a total of 39 moths captured. In comparison, only two western bean cutworm moths were trapped last season, again both in Cass County. This insect appears to have moved further north and east in the Michigan. Why the concern? Western bean cutworm has moved rapidly cross the Midwest from west to east. The major feeding sight for western bean cutworm larvae in August is in the ears. In some western states, larvae cause severe damage late in the season. Spray applications are made, or growers must choose among different Bt hybrids. Moth numbers are still low in Michigan, and we have NOT documented feeding in ears by western bean cutworm larvae. But in scouting corn in mid- to late-August, be alert for what appears to be “giant corn borers” in ears – this may be western bean cutworm, but there are several caterpillars that feed on ears, such as European corn borer, earworm and armyworm. Collect specimens if possible and preserve them in alcohol – commercial grade ethanol, vodka, tequila, etc. Rubbing alcohol can be used in a pinch, but it isn’t as good of a preservative. Bring the specimens to your county extension office so they can forward them to Howard Russell or me, Chris Difonzo, at the MSU Diagnostic Services. I will coordinate trapping of moths again in 2008, and would like to expand the numbers of counties in Michigan. If you live in, or cover, a county that wasn't trapped in 2007, email me (difonzo@msu.edu) if interested, and I'll put your name on my list for next year. For the future, here are several free western bean cutworm references on-line:
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| Do I have enough soil moisture to make a crop? The dry conditions of the 2007 growing season to date have many wondering if they have enough soil moisture to finish out their corn and soybean crops. A few simple calculations can give us a pretty good idea whether or not we have a chance of making it to the finish line. For starters, we know that a 150 to 200 bushel corn crop or 50 to 60 bushel soybean crop require approximately 20 to 24 inches of water. By adding up our seasonal rainfall and estimating the amount of water stored in our soil profile, we can get a pretty good idea if we have adequate moisture available to reach our yield goal. For example, my field consists of a Blount loam soil. By checking a USDA Soil Survey or by looking up the USDA, Natural Resource Conservation Service web-based Soil Survey at: http://websoilsurvey.nrcs.usda.gov and following the prompts, I can get a good estimate of my soils water holding capacity. In my particular case with a Blount loam soil, the water holding capacity is listed as: 0.17 cm per cm in the top 36 inches of soil. The cm per cm unit is actually a straight percentage so: 36 inches x 0.17 percent = 6.12 inches of available soil water in the upper 3 feet of soil assuming I start at field capacity in the spring. The next step is to add in the amount of rainfall received since planting. If you don’t record this information for yourself, you can use precipitation data recorded at the “Michigan Automated Weather Network” (MAWN) station nearest your field which can be accessed at: http://enviroweather.msu.edu/home.asp. Checking the MAWN website, I find that I have received only 6 inches of rainfall in my vicinity since planting. Assuming that I began the season with my soil moisture at or near field capacity, I calculate: 6 inches of rainfall received + 6.12 inches stored soil water = 12.12 total inches of available water. This leaves me a water deficit of 8 to 12 inches short of the precipitation levels needed to meet my yield goal. What are the chances I’ll get another 8 to 12 inches of rain while my crops can still benefit from it? By using 30-year average rainfall data I can get a pretty good idea. Thirty-year average precipitation levels are available at: http://climate.geo.msu.edu/. The 30-year average August rainfall in my area is about 3.8 inches. If August precipitation levels are near average, my total crop available precipitation would then be just short of 16 inches (12.12 inches +3.8 inches) which is still considerably short of the 20 to 24 inches desired. The 30-year average data also show that I could expect another 3.8 inches in September, but most of that would likely be too late for the corn plant to benefit in terms of grain yield. Therefore, it appears that 2007 precipitation levels will likely limit my corn and soybean grain yields below my targeted yield goals. Of course these calculations should be considered “ballpark estimates” as actual soils vary considerably in terms of water holding capacity. Additionally, crop rooting depth will vary based on soil structure, crop genetics, nutrient status, and early season water levels. |
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| Soybean disease update and fungicide use Many areas of Michigan are suffering from severe drought. I just listened to an hour of reports from extension educators across the state talking about how much of the state’s corn crop has been lost. However, there still seems to be some hope for a decent crop of soybeans. Some areas of the state have received a bit of rain recently, although predictions of above normal temperatures and lower than normal rainfall continue. Growers are all hoping for the best, looking for ways to squeeze out more yield. Growers have had to face serious issues with drought, spider mites, bean leaf beetles, Japanese beetles and other problems. With all these other challenges, at least foliar diseases have not been a problem in soybeans. Soybean rust has stayed out of Michigan, and conditions do not look favorable for spores to travel north from the Gulf Coast area for the next 8-10 days. Other foliar diseases such as brown spot and Cercospora leaf spot have been at very low levels, and certainly not approaching any kind of threshold. So, we are back to the same issue that was discussed a couple of weeks ago in the CAT Alert – using a fungicide in the absence of a specific target pest, for its “plant health” benefits, specifically, yield increase. Using any kind of pesticide in the absence of a specific pest runs strictly against the principles of integrated pest management. One of the consequences always thought of is the risk of resistance developing from repeated fungicide use. We don’t always think about other unintended results of applying fungicides, such as “…the suppression of native fungi that naturally keep insect populations in check. There is already some evidence that indiscriminate use of fungicides in soybean has resulted in increased insect/mite activity in some states.” Not a particularly good idea to further suppress beneficial fungi, especially if you are already experiencing spider mite or insect flare-ups in your fields. Another unintended consequence “…could be stricter future pesticide laws and regulations.” (The Integrated Crop Management Newsletter, Iowa State, June 26, 2006.) Growers who are thinking about making a fungicide application for “plant health” benefits should be aware that there is no magical formula to predict a significant economic return. Although a positive yield effect may take place, it may not. There isn’t enough information to determine in advance which fields/situations will respond with an economic yield increase and which ones won’t. |
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| 2007 soybean yield contest 2006 was the first soybean yield contest in Michigan, with a high yield of 71 bushels per acre. For 2007, soybean farmers in Michigan are encouraged to consider entering one or two fields into a soybean yield contest. The Michigan Soybean Promotion Committee and Michigan State University Extension are sponsoring this yield contest. The contest is a “fun” way to encourage farmers to get higher yields of their soybeans because they will be recognized for this by their peers and the soybean industry in Michigan. This contest is part of a Soybean 2010 initiative designed to increase soybean yields in Michigan. Corn and wheat yields in Michigan have increased dramatically in the past ten years, but soybean yields have not. This contest is based similar to the National Corn Grower contest. There will not be a re-checking of yields in this case and there are other differences. Entry forms are now being mailed to farmers and are available to farmers through the Monroe County Extension Office. Farmers with interest can contact Ned Birkey at 734-240-3170 or Mike Staton at 269-657-7745. Entry forms and a $25 per entry fee must be postmarked by August 18 and mailed to the Monroe County Extension office. |
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| Development of drought conditions in Michigan Scattered showers and thunderstorms brought some much needed rainfall to a few locations across Michigan during late July, but the rainfall was localized and drought conditions persist in many areas of the state. For the growing season thus far (beginning April 1), precipitation deficits have grown in many areas to the 3-5 plus inch range, although these figures are somewhat misleading since the majority of the drier than normal conditions have taken place since early June when crop water needs are relatively greater. Normal precipitation for this time frame is on the order of 11.5-13.0 inches. Precipitation totals across the state as estimated by National Weather Service radar are given in Figure 1 and illustrate the areas of greatest deficits including areas of southwestern and eastern Lower Michigan as well as the western Upper Peninsula where totals remained less than 25 percent of normal. In some areas of the state, July 2007 will go into the books as one of the five driest on record. Meteorologically, the dryness has been associated with a persistent upper air ridging feature anchored across western North America that has reduced the amount of low-level moisture flow (the “raw material” of precipitation) into the Great Lakes Region. As of the beginning of August, drought conditions were reported across sections of the Upper Midwest in Minnesota, Wisconsin and Michigan southward through the Ohio Valley into the southeastern United States. These patterns are illustrated in the most recent version of the Palmer Drought Severity Index (Figure 2), which depicts areas of long term precipitation surpluses and deficits. Note that some of the drought conditions in Michigan have now slipped into “Severe” and “Extreme”categories. Figure 1. Percent of normal precipitation between June 2 and July 31, 2007. Precipitation values are based on National Weather Service Stage III precipitation estimates (courtesy of the National Oceanic and Atmospheric Administration). As an example of the gradual depletion of soil moisture, volumetric soil moisture at a 10-inch depth under grass taken from the MAWN automated weather station at East Lansing is plotted versus time and with daily precipitation totals in Figure 3. The soil at the site is capac loam. Soil moisture can be seen to decrease from a value of approximately 0.25 inches³/inches³ following the rainfall of early June to about 0.10 inches³/inches³, then peak once again in late June following a 1.3 inches rainfall event before falling to its end of July level of approximately 0.08 inches³/inches³, which is near the soils wilting point. |
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| Drought on-line resource now available With this season facing drought conditions, a new online resource offering helpful tips and information has been established. Please visit http://www.ipm.msu.edu/drought2007.htm. Topics include: general drought and crop information, effects on corn and forages. This site will be updated as articles come in from the Field Crop Area of Expertise Team and CAT Alert authors. –Andrea Buchholz, asst. editor. |
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| Regional reports 1 -- Southeast Ned Birkey Weather The weather has turned around with up to eight inches of rain, primarily near the state line area, since two weeks ago. Everyone has had some rainfall, and areas near Adrian, Blissfield and Ann Arbor had hail two weeks ago in a storm that gave some farmers up to four inches of rain. Last Friday a flash drought report was going to be filed for Washtenaw County. Monroe and Lenawee already qualify as contiguous counties to northwest Ohio, which has already received a drought status. We still have high temperatures, but the rains have also brought very high humidity when the sun comes out. Crop reports Alfalfa hay is in very short supply, with small square bales of hay being shipped to Lima, Ohio: Lexington, Kentucky and Florida this summer. One rumor, from a fairly reliable farmer, is that a local farmer who is trucking hay to Kentucky is making a $4.00 per bale profit. Most second cutting has been bringing about $4.00 per bale locally and there does not seem to any surplus hay on hand. Third cutting should see much more hay. Some farmers are spraying for potato leafhoppers. Corn is pollinated and in the blister to milk stage. The rains of the past two weeks have benefited everyone who has corn as we are in the all important kernel fill stage. Even with the rain, it has come too late to benefit some three-foot tall fields. One local chemical company has been spraying corn for gray leaf spot. It is surprising to see how green many cornfields are. I think improved genetics is responsible for drought resistance as it is unusual to see lots of lower leaves firing anymore. Soybeans are still growing, flowering and podding. Soybean aphids can be found, though not at threshold levels. Spider mites are the main problem, though recent rains will help soybeans compensate. You can find as many potato leafhoppers in soybean fields as aphids. Japanese beetles are plentiful and are still feeding, though I have not seen any fields near the 25 percent leaf loss threshold. Some fields are showing severe brown spot and bacterial pustule. One local company sprayed over 600 acres with Stratego and “bug juice” this past week. One farmer was worried about Asian soybean rust. Another farmer had a soybean field sprayed, as he did not want any more insects feeding on “his beans.” He was talked into using a foliar fertilizer applied at the same time. The company spray “jockey” refused the farmer’s request to leave a check strip on untreated soybeans. Wheat ground is being mowed and the straw baled as wheat straw is fetching up to $5.00 per bale in northeast Indiana. Weeds are coming up, and some fields are being deep ripped or having field drainage tile installed. At last week’s fair, one farmer reported that the previous week’s rains had not reached down into the subsoil where the tile machine was working. The Nabisco Flour Mill of Toledo is using more soft white wheat and will be encouraging more farmers to raise white wheat varieties. They have some varieties identified that make for higher quality flour for baking purposes. Miscellaneous Farmers here are being taken advantage of by some people who are selling pesticides and saying that yields will increase up to 30 bushels per acre, even though fields are not at threshold for spraying of insects or diseases. Hay looks to be in very short supply this winter as our crop supply is down this year and hay is already being shipped to other areas. |
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| 3 -- West Central Fred Springborn Weather Rain showers two weeks ago were more limited than what was first thought. One to two inches of rain did fall across much of Montcalm County, but much of the southern portion of the county was missed as well as some areas to the north. Newaygo County received 0.8 inch of rain since the 2.0 inches on July 4. Rains across the entire region have been highly variable with some areas receiving much less and some more. High temperatures for the last two weeks have been in the mid 80s to low 90s. Crop reports Corn is variable. Irrigated corn is progressing well with many fields in the dough stage and excellent yield potential. Dryland corn is variable from very poor to better than what might be expected with such little rain fall. Pollination of this crop is complete with variable success. European corn borer trap catches are very low with most traps catching one to two moths. Corn earworm trap catches have picked up again this week with an average of five moths per trap. No western bean cutworm has been detected this year in Montcalm County. Irrigated dry beans are in very good condition where there is adequate moisture. Dryland beans are suffering from drought stress, most fields are flowering and setting pods. Where soils were allowed to dry out before planting, stands are poor. Weed control has also been fair to poor in many dryland bean fields. Soybean fields are setting and filling pods. Plant size is below normal. Low numbers of soybean aphid have been observed. Spider mites are present in many fields, some above threshold. Potato leafhopper, bean leaf beetle, grasshopper and other minor pest are also present. Alfalfa second and third cuttings are continuing. Yields are very low, it is estimated that the hay crop will be no better than 60 percent of normal (40 percent loss). There is slow spotty re-growth due to dry weather and leafhopper damage in some fields. Pastures in Newaygo County are in severe drought condition, winter hay is being fed on most farms. Sugarbeets are doing well by and large. Even irrigated beets have shown moisture stress on several days when temperatures were high and humidity was low. |
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| 4 -- Central Dan Rossman Weather Small amounts of rain were not enough to make much of a difference. Some areas have been missed by rain altogether. The extreme dry and hot conditions are a very serious situation over the region. Crop report The corn crop is firing up from the bottom. Some fields have been chopped for silage already. Yield loss will be substantial. Soybeans have had very little growth in the last two weeks. Spider mites are easily seen along field margins. Aphids are now present and increasing in numbers. Most are still well below threshold, but need to be scouted closely. Grubs are killing soybeans on sandy ground in a few pockets in the area. Pod set appears to be very light. The oat crop is harvested. Yield and test weight is lower than normal. Alfalfa has had nearly no re-growth over the last few weeks. Hay is in short supply. Dry beans are in bloom or setting pods. Leafhoppers and dry weather are taking their toll on this crop. |
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| 5 -- Thumb Mark Seamon Weather To be consistent with almost all rainfall this summer, the showers on Monday, August 6 helped some areas and left others wanting much more. Rainfall amounts ranged from more than 2 inches to a couple of tenths of an inch. Crop reports Alfalfa re-growth is slow and providing very short second and third cuttings. Beets are taking advantage of the rain where it fell. Cercospera leafspot is the biggest topic in sugar beets now. Disease Severity Values from the Beet Cast system are variable across the beet growing area. Leafspot symptoms have been limited, but the recent rainfall has caused a lot of leaf wetness. Be sure to check specific data for a site near you. This can be found at www.MichiganBeets.com Sugar beet cyst nematode feeding can be seen in many fields. Corn has pollinated pretty well in most areas. Drought has limited pollination in some places and has caused some kernel abortion after pollination in other areas. Fields in dry areas with lighter soils or variable soils are showing a lot of firing of lower leaves with some plants nearly dead. The soybean crop is also struggling with the dry conditions with very slow growth. Bean leaf beetles are feeding in most fields with those slow growing fields showing defoliation up to 20 percent. Soybean aphids are still present in most fields, but variable within fields and between fields. A few reports of fields with aphids over the 250 per plant threshold have been sprayed, but most are well below threshold. Dry beans have been affected by the drought conditions as they blossom with poor pollination and pod set. Longer maturity and later planted beans may benefit from the rainfall this week. |
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| Weather news Jeff Andresen Agricultural Meteorology Geography Showers and thunderstorms brought more rainfall to many areas across southern Lower Michigan during the last few days, while central and northern sections of the state were largely missed. Overall, drought conditions continue to be a major problem in many areas of the state. Unfortunately, forecast guidance does not suggest any major changes to the current and recent past weather upper air pattern, with a general continuation of heat and dryness expected over much of the region during the next week. The morning of Thursday, August 9, a weak frontal boundary stretched from an area of low pressure over the Canadian Maritimes westward through the Great Lakes and Great Plains regions. A second area of low pressure is expected to ride eastward along this front during the next 24 hours, bringing another round of showers and thunderstorms to sections of Michigan before it moves south of the state late Thursday evening. At this point, best chances for precipitation will be across southern sections of the Lower Peninsula, with decreasing chances north of this area. Rainfall totals will generally be in the 0.25-0.5 inch category, with some isolated 1.0 inch amounts possible, especially along the Indiana/Ohio border. High pressure will move in behind the low pressure, leading to fair and dry weather statewide on Friday and Saturday. Temperatures during the next several days will remain at above normal levels, with highs ranging from the upper 70's far north to near 90ºF south and lows from the upper 50's north to mid- and upper 60's south through Saturday. The next chance for rainfall after Thursday will likely come late Saturday and Sunday in association with a frontal system approaching from the northwest. Given limited low-level moisture ahead of the front, any precipitation is expected to be scattered in nature, with many areas remaining dry. For a change, best chances for rain with this system will be across western and central sections of Upper Michigan. In the medium range time frame, both 6-10 day and 8-14 day outlooks, covering August 14-18 and August 16-22, call for a continuation of above normal temperatures state- and region-wide. Precipitation totals during the 6-10 day time frame are forecast to range from below normal levels in southern Lower Michigan to above normal over the Upper Peninsula. During the 8-14 day period, precipitation totals are expected to range from below normal levels across southern sections of the state to near normal levels in the north. |
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