Vol. 19, No. 2, August 26th, 2004

In this Issue
Will corn and soybeans reach maturity before the first killing frost date?
Regional reports
Some summer-like weather.finally

Will corn and soybeans reach maturity before the first killing frost date?

Kurt Thelen
Crop & Soil Sciences

The cooler weather we have had this August combined with the later planting dates experienced this spring has many growers wondering if their corn and soybean crops will mature before the first killing frost. Of course, it is impossible to tell for sure when the first frost will occur or how many GDD units we will acquire until then. However, we can use long-term weather data to make an educated guess. The estimated date of the first killing frost, which is generally considered to be 28°F, can be obtained from the Michigan State Climatologist's website at: http://climate.geo.msu.edu/mi-map.html

Simply click on your location on the state map and then select the "First fall temperature threshold date" prompt.

Now that you have determined the date by which you have a 50 percent chance of having received a killing frost, you will need an estimate of the number of growing degree days you will likely receive between now and the first killing frost date. To do this, visit the MSU Agricultural Weather Office website at: http://www.agweather.geo.msu.edu/

Select the "Current weather" icon and then locate the station nearest your location under the "Daily Temperature and GDD Normals" column. This will provide you with the 30-year average daily GDD accumulations. Simply determine the number of available GDD's from the current date to the estimated first killing frost date determined above.

As a general rule of thumb, corn grown in Michigan will require approximately 225 GDD units to progress through each of the following grain-fill developmental stages: blister to dough; dough to beginning dent; beginning dent to full dent; and finally, full dent to blacklayer formation. Research has shown that late-planted corn does have a limited ability to speed through growth stages faster than earlier planted corn, however, the 225 GDD provides a good figure for estimation. Using this rule of thumb as a guide, you can now estimate at which growth stage you need to be at now to have a reasonable (50%) chance of your corn reaching full maturity prior to the first frost. The following table shows the estimated stage of development needed by August 20 for several Michigan locations to reach maturity before the estimated first killing frost date.

A cool fall will not significantly delay maturity in soybean. Unlike corn, maturity in soybean is strongly influenced by photoperiod (day length). The rapidly increasing length of the nights (dark period) during late August is what signals the soybean plant to begin filling grain - temperature plays a less important role in this process. Therefore, as long as a reasonable planting date (prior to June 25) and an appropriate maturity group (Group 2.5 or less for most of mid-Michigan) was used, soybean will usually mature prior to the estimated first killing frost date.

Regional reports

1 - Southeast

Mike Score

Commodity reports
Farmers are realizing just how spread-out this year's corn crop is. Silage producers have some fields in early dent stage while others have not tasseled yet. Even fields where pre sidedress nitrate testing was done are showing signs of nitrogen deficiency. Kernel counts of corn in fields with excellent yield history show wide ranging yield potential with highs in the mid 200 bushel range and lows in the 120 to 130 bushel range.

White mold is present in soybeans in southeast Michigan. The severity of infection is not adequately judged from roadsides. Inspection out into fields reveals fairly common and extensive infections in some fields. Aphids and spider mites have been held in check, for the most part, by continued rainfall through mid-August.

The consensus is that hay quality will be low throughout most of our region. Timing of hay harvest operations has been near impossible for most producers. First cutting of alfalfa was severely delayed by rainfall through June. Throughout the summer most fields were rained on at least once following cutting operations.

2 - Southwest

Bruce MacKellar

Weather
Dry conditions continued over much of the southwest region until a warm front brought some much needed heat and rainfall to the region on August 24-26. Rainfall totals were still variable, but precipitation levels ranging from 0.5 to 1 inch were fairly common. The higher rainfall totals were found in extreme southwest portions of the region. Before this time, crops were being irrigated or were beginning to suffer from drought stress. Cool temperatures since the August 12 CAT Alert have led to the slow development of both corn and soybeans. GDD50s are now at the 30 year normal mark for Battle Creek and Three Rivers, but the late planted crops were not able to take advantage of the early GDD accumulations.

Commodity reports
Corn ranges from recently pollinated to early dent in southwest Michigan, all depending on the date of planting and the relative maturity of the hybrids. Most insect problems have been fairly light this year. Chris DiFonzo's crew made a root digging trip through our region in early August to evaluate first year corn for western corn rootworm variant feeding. Results varied by location, with pockets of areas in several counties showing pruning in first year fields and other areas showing little or no sings of feeding. Dan Rajzer reported that some of the fields in Cass County are beginning to show signs of nitrogen loss earlier in the season. I have seen this on some of the higher population irrigated commercial corn fields in St. Joseph and Kalamazoo Counties as well.

Seed corn pollination has been completed in most fields and male row destruction is well underway. Some inbred lines have been challenged by leaf rust in southwest Michigan this season. Fungicide applications appear to have been effective in controlling the impact and spread of the disease through the plants.

Soybean development continues to be worrisome in the region. Plants have been struggling all season long to set pods. Many plants are only at the early to mid pod fill stages (R4,R5, R6). Having said this, some of the earliest planted soybeans are beginning to show signs of senescence. It appears that soybean harvest is likely to be a long and drawn-out process for many growers this year. Soybean plant size and development remains all over the board this year. You can see the effects of the wet spring in many fields, which have pockets of yellowing soybeans. We think that some of this may be attributed to root diseases. There are also many fields showing signs of soybean cyst nematode infestation. We are also seeing some sudden death syndrome in soybeans this year. Most of this has been in St. Joseph County on fields where SCN can be found in at least low numbers. SDS appears as a rapidly developing yellowing, followed by necrosis, of upper leaf tissue between the veins.

There is also some yellowing symptoms that appear to be associated with potassium deficiency on extremely sandy soils. This may be due to leaching of applied potassium on deficient soils earlier in the season. Soybean aphids are few and far between this year in the southwest. I would like to note, however, that there has been a substantial increase in the number of fields where soybean aphids can be found over the past week. The numbers of aphids remain very low. However, if conditions should become warm and dry, aphid numbers are capable of rising rapidly. Keep an eye on soybean aphid numbers, particularly on your latest planted fields.

3 - West Central

Fred Springborn

Weather
High temperatures ranged from 64 degrees to 82 degrees over the past two weeks. Only five out of the last 14 were above 75 degrees. Low temperatures dipped into the 30s on August 21 and 22. Light frost damage has been observed in several locations - no significant damage occurred. Rainfall totals have been variable. Most areas of the region have dry surface soils.

Commodity reports
The fourth cutting harvest of alfalfa is progressing on a few farms. A few farms are still working on the third cutting.

Second cutting is nearly complete in mixed hay. Much of this hay was put up with little rain damage.

Harvest is generally complete in all small grains. Yields for oats and barley have been generally good.

Corn condition overall is fair to good but growth is behind normal. We still need some good summer time weather to make this crop.

Soybeans, like corn, are variable in condition and growth stage. Soybean aphid numbers remain low. Dry beans are growing well overall but are behind normal in development. We do have a few fields turning but none yet harvested. The first cranberry beans are probably four or five days away from harvest.

4 - Central

Paul Gross

Weather
The region has been very dry over the past month. The southern part of the region has received scattered showers over that time frame while the north has had only trace amounts. There was some relief on Wednesday evening (August 25) with showers bringing anywhere from one half to over one inch of rain. The cooler weather, while slowing crop progress kept stress levels low. The northern part of the region had light frost on August 21 and 22.

Commodity reports
The corn crop varies widely across the region. The variability depends on planting date and the amount of rain the fields received. There are fields that will have average yields while there are fields that will not make harvestable grain. The weather in September will need to be favorable and will determine what kind of yields we will have.

The soybean crop is just as variable as the corn crop. Many of the early-planted fields are showing signs of maturing while others are flowering with few if any pods. The weather in September will determine the fate of the crop in the field.

Most alfalfa growers are waiting to harvest third cutting. The dry weather will greatly reduce yields. First and second cutting yields were very good so most livestock feeders have adequate supply however quality is below normal. New seedings are emerging slowly so the rains this week will benefit these fields.

Sugar beets look good. Some fields are showing sign of nitrogen deficiency.

Dry bean fields are generally good but will need a good September to mature the crop.

5 - Thumb

Mark Seamon

Weather
Limited soil moisture and cool temperatures are the limiting factors in crop development throughout this area. A few areas have received spotty rainfall, but this is the exception more than the rule. The recent warmer temperatures have been a welcome change to our weather pattern.

Commodity reports
The alfalfa crop has slowed growth due to limited soil moisture.

In sugar beets, Cercospera Leafspot has been developing a faster with warmer temperatures in the past week. This seems to have led to more fungicide applications, some for the first time and some the second application. Weed escapes are showing through in many areas.

Corn development has been pretty slow until the past few days when we have received warmer temperatures. Weather conditions during pollination were very good and have led to full ears. The million dollar question remains: Will we receive adequate growing degree days before a killing frost to mature and start dry down of corn grain?

Crop development has been slow in soybeans with many plants having very small pods that will need a significant amount of time to produce a harvestable bean. Lower pods look good but there are not enough lower pods to make even an average yield. This crop seems to be in the same position as corn; weather in the month of September will be critical.

Many dry bean fields are showing maturity now. A few early fields of black beans may be harvested within 10 days but most will be delayed well into September. Maturity of plants within fields is variable which has been caused by stresses throughout the growing season.

6 - Northern Lower Peninsula

Dave Glenn

Weather
Cool and cold weather has hung over the north for a week or more. Frost hit several lower areas, burning some dry beans last Saturday morning (August 21). Lows got down to 34°F. Moisture has been intermittent, but not enough to really benefit the crops. Irrigation continues to run on potatoes.

Commodity reports
Corn is still looking pretty good. Early corn is starting to show milk. Corn stills needs a good 45 to 60 days or more to make a good crop.

Wheat is all harvested with yields ranging from 40-80 bu/acre. No vomitoxin has been noted to date with most wheat being sold with premiums for being clean. Test weights are running high ranging from 57-61.

Soybeans are starting to turn color in some fields with the beginning of leaf drop. The crop is going to be on the poor side of good with short plants, small pods and a long way to go.

Dry beans are looking good, but are nowhere near being finished. Some low areas with beans were hit by the frost on August 21. A second set of pods seems to be coming on in some fields. Yields night average around 10-15 cwt/acre.

Second cutting of alfalfa is all done with tonnage at average or above thanks to the cool and moisture weather this summer.

Oats are just starting to come off the field now with most fields looking pretty good. Rye is all off also.

Potatoes range from still flowering in very late potatoes to drying down in others. Set seems to be pretty good with 7-14 tubers per plant although size is suffering a little.

Some summer-like weather.finally

Jeff Andresen
Agricultural Meteorology
Geography

Major changes in the jet stream orientation across North America have taken place during the past several days with the formation of a trough across western sections of the continent and a broad ridge across the east. Thursday morning (August 26), a warm and humid subtropical air mass was entrenched across Michigan and much of the Great Lakes region. A cold front will very slowly make its way eastward into the state by tomorrow, but the front is expected to slow even further or stall out over southern sections of the Lower Peninsula by Saturday. With very warm, humid air in place, showers and thunderstorms are possible on a daily basis through Saturday, and possibly into Sunday in southern sections of the state. While areal precipitation coverage is expected to be scattered (There will be no clear focusing mechanism such as a strong front.), severe weather (primarily high winds) and heavy rainfall totals are possible due to the high dew point temperatures and slow forward movement of any thunderstorms that do form, especially Thursday and Friday evenings.

Further ahead, the front mentioned earlier will finally clear the state by late in the weekend and result in fair, cooler, and drier weather for the early part of next week. Temperatures will remain at above normal levels through the end of the workweek with highs ranging from the upper 70's and low 80's north to the mid and upper 80's south (High temperatures in southern sections may approach 90°F Friday should skies remain mostly sunny.). Low temperatures will range from near 60 north to near 70 south. Look for cooler temperatures by late in the upcoming weekend with highs falling back to the upper 60's north to the 70's south and lows back into the 40's north to 50's south.

The upper air change mentioned above is generally expected to continue for the next one to two weeks, leading to a relatively warm and unsettled period across the Great Lakes. The NOAA CPC 6-10 day and 8-14 day outlooks for August 31 through September 4 and September 2-8 call for above normal temperatures to continue across the state and region. Precipitation totals during the 6-10 day period are forecast to be above normal statewide, and range from near normal in northwestern sections of the state to above normal over most of the Lower Peninsula in the 8-14 day time frame. This is obviously a favorable forecast given the significant portion of summer crops in the state that lag far behind normal phenological development stages at this point in the season due to spring planting delays and to unusually cool summer temperatures.

New long lead outlooks

Warmer than normal sea surface temperatures along the equator across sections of the Pacific Ocean suggest the beginning phases of an El Nino event. Current indications are that the El Nino will be relatively weak, which typically means that the climatic anomalies usually associated with El Nino events will be absent or weak themselves. Even so, new NOAA Climate Prediction Center long lead outlooks for Michigan and the Great Lakes region during the upcoming months are strongly leading towards an El Nino type of winter and spring (milder and drier than normal). The outlook for the month of September is a different story. The official outlook calls for cooler and wetter than normal weather over all of Michigan and large parts of the Midwest. However, this outlook is based primarily on the persistence of the upper air pattern of late July and much of August, which has recently changed (as noted above).

In the longer term, the outlooks for mean temperature and precipitation for the 3-month September-November through November-February periods are the climatology scenario of equal odds of below-, near-, and above normal values. Beginning in mid-winter and continuing through mid spring of 2005, however, the outlooks increase the odds of a milder and drier than normal winter for much of the Upper Midwest including Michigan. Again, should the forecasted El Nino event remain weak or not occur at all, this outlook would have to be modified.