Soybean aphids hatching in Mid-Michigan |
As of Saturday, April 17, tiny soybean aphids were present on potted buckthorn near the MSU campus. See the April 8, 2004, CAT Alert for an article on soybean aphid overwintering and crop colonization
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Soybean aphid, Part 2: Scouting for aphids in 2004 |
After soybean aphid (SBA) damaged many fields in 2003, most people realize that scouting for aphids can pay for itself. Although SBA is a relatively new pest in the U.S., researchers have learned a lot about this insect in the last several years. In December 2003, entomologists from 11 universities plus the Canadian government met in Chicago for a one-day work session on SBA. By the end of the day, we reviewed data from field trials across the Midwest, and developed consensus recommendations for scouting and treatment thresholds for the 2004 field season. Below is a summary of this consensus. You can also find this information in a 15-page glossy bulletin produced by the North-Central Soybean Research Program (NCSRP), published as an insert in a March issue of the Soybean Digest Magazine. It is also available online in a slightly different form at the NCSRP's Plant health Initiative web site at: http://www.planthealth.info/soyaphid.htm Finding aphid on soybean § Look
for plants with ladybugs. Ladybugs are looking for lunch, and they
are better than you at finding small aphid colonies on plants. Scouting What? Examine whole plants. In the past, I tried to develop a rating system to quickly assess the numbers of aphids per leaflet or leaf. These rating systems worked well when we had thousands of aphids per plant or evaluated an insecticide trial. But they don't work as well to determine if aphid numbers are at threshold. Also, researchers found that aphids redistribute themselves on the plant as the season progresses, probably due to temperature or nutritional status of different parts of the plant. This made it difficult to develop a rating system based on a particular plant part. Bottom line, entomologists across the Midwest agree that whole-plant counts are the preferred method to scout for aphids, and the threshold for soybean aphid (see following section) is based on a whole-plant count. Where? You can scout for aphids at any location in your field. Research in Minnesota tracking aphid colonization of fields shows that "edge effects" are weak for SBA. Edges of fields next to buckthorn do get aphids a bit sooner than other parts of the field, but by the time many winged aphids appear in the population, they move around the landscape and rain out across the field. In Michigan, we do find hot spots associated with low potassium levels - high numbers of aphids in yellowing patches - but this usually occurs later in the summer when aphid numbers in general are already over threshold. How long? For the most part, optimum spray timing occurs between mid-July into early August, so scouting should be targeted across that time period. You may have to visit fields several times in July to determine if aphid numbers are increasing towards threshold (In 2002, they did not!). If you have limited time, continue to check untreated fields in favor of revisiting treated fields - the majority of data I've seen does not show an economic advantage to treating twice, so it is unlikely you need to continue scouting to make another application. Remember, in 2003 aphid numbers increased later in the season at some locations in the Thumb, so I can't rule out checking unsprayed fields in August. Pay attention to: § Fields
with buckthorn nearby (colonized earlier in the season) The threshold Why build extra time into the threshold? If you couldn't take action immediately when insects are at the point of causing $12 loss (For example, it rains before spraying or you need to purchase insecticide.), then you would already be losing significant yield by the time you treat. The seven-day spray window for soybean aphid is a bit longer than most, but for good reason. First, data from the laboratory shows that under optimal temperature conditions (77°F) SBA populations can double in 1.5 days. This is one of the fastest doubling times recorded for an aphid. This also explains why fields seem to go from OK to bad in a matter of days! So, providing a few days buffer allows you to recognize aphids are at threshold and do something about it before suffering yield loss. Second, from experiences in 2003, we know when aphids become a problem on one farm, they are often a problem across an entire region. You need a spray, your neighbor needs a spray, everyone needs a spray. Commercial applicators may have trouble meeting demand in a short time frame. We also had shortages of certain insecticides in 2003. A seven-day spray window eases some of this pressure so that you can afford to wait a few days before application. So, again, the threshold for 2004 is 250 aphids per plant - and this threshold was agreed upon by most Extension entomologists in the Midwest. One final practical note § Most,
if not all, of the plants will be infested. So, if 90 percent of the plants in a field have multiple, heavily-infested leaflets, plus some aphids beginning to infest stems, for practical purposes the field is likely near or at threshold. In the May 6 edition of the CAT Alert, I will discuss soybean aphid and insecticides. |
How much N is needed for corn production? |
This article is a follow-up to the February 6, 2004 article
titled Begin Planning Your Nitrogen Applications Now. That
article summarized the findings of a study conducted in 2002 and
2003 regarding N rates for corn and performance of the PSNT. The
data presented in that article can also be looked at a little differently
to gain some insight into how much N is needed for corn production.
Table 1 provides the maximum and economic yield and N rate for all
14 locations. Economic yield was determined by calculating the N
rate above, which the income from the additional yield was not larger
than the cost of N needed to increase yield. This was accomplished
using $2.00/bu corn and $0.20/lb N. The economic yield would be
the same for $3.00/bu corn and $0.30/lb N or $2.50/bu corn and $0.25/lb
N. Nitrogen efficiency was calculated by dividing the N rate needed
to produce the maximum or economic yield by that yield, resulting
in the pounds of N required to produce a bushel of corn. One might ask: What does all this mean? Is it a result of two years with dry weather conditions in late summer? Good questions. I don't think that the results are specific to weather conditions because researchers in Minnesota, Nebraska and Wisconsin have had similar findings in recent years. Is it related to better genetics or higher fertility status of our soils? Perhaps, researchers don't really know for certain. The question then is: How do I use this information? Considering that the price of N today is still on the high side, ranging from $0.27/ lb N for urea to $0.32/lb N for 28% UAN, one might think about adjusting N rates. For example, if you are using MSU's N recommendations with a 150 bu yield goal, you would apply 175 lb N/a ([1.36 x yield goal] - 27 = 177). So if you dropped your N rate back to 1 lb N/bu (greater than any of the efficiencies for maximum yield in Table 1), you would apply 25 lb less N, saving $6.75/a to $8/a depending on your N source. Remember that the N efficiencies for economic yield are lower than maximum yield. Thus, it may be possible to reduce N rates further (eg. 0.9 lb N/bu), saving even more money. Based on the data shown in Table 1, the probability of short changing yourself on yield is minimal and the probability of saving on input costs is high. An additional benefit to reducing N rates is that lower amounts of unused N will create fewer water quality concerns downstream. This study is being conducted again in 2004 with locations in Barry, Calhoun, Cass, Clinton, Ingham, St. Clair, and Osceola counties. Perhaps this time next year we will have more answers.
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Table 1. N required for corn production in 2002 and 2003.
|
|
--------
Yield -------- |
-----
N rate for: ----- |
-----
N Efficiency ----- |
|||
|
Location |
Maximum
|
Economic |
Maximum
Yield |
Economic
Yield |
Maximum
Yield |
Economic
Yield |
|
|
---------
bu/a --------- |
--------
lb N/a ------- |
--------
lb N/bu -------- |
|||
|
2002 |
|
|
|
|
|
|
|
Barry |
143 |
140 |
119 |
112 |
0.83 |
0.80 |
|
Ingham |
151 |
142 |
73 |
62 |
0.48 |
0.44 |
|
Saginaw |
159 |
153 |
109 |
96 |
0.69 |
0.63 |
|
2003 |
|
|
|
|
|
|
|
Barry |
169 |
162 |
100 |
100 |
0.59 |
0.62 |
|
Cass |
138 |
126 |
58 |
50 |
0.42 |
0.40 |
|
Calhoun |
137 |
127 |
100 |
0 |
0.73 |
0 |
|
Gratiot |
179 |
173 |
100 |
100 |
0.56 |
0.58 |
|
Ingham
1 |
143 |
143 |
112 |
112 |
0.78 |
0.78 |
|
Ingham
2 |
154 |
160 |
136 |
120 |
0.88 |
0.75 |
|
Monroe |
194 |
184 |
113 |
100 |
0.58 |
0.54 |
|
Montcalm |
171 |
169 |
57 |
54 |
0.33 |
0.32 |
|
Osceola |
155 |
145 |
66 |
50 |
0.43 |
0.34 |
|
Saginaw |
171 |
163 |
131 |
90 |
0.77 |
0.55 |
|
St.
Clair |
134 |
123 |
130 |
54 |
0.97 |
0.44 |
Micro-rate herbicide applications underway in 2004 |
Warm spring weather and the recent rains have given sugar beets and weed seedlings a jump in emergence compared to the last several years. This early emergence starts the beginning of micro-rate herbicide applications. Timing these applications is critical in providing good weed control and reducing sugar beet injury. Over the last couple of years, several growers have moved to timing micro-rate herbicide applications based on growing degree days (GDD). From recent surveys, approximately 45 percent of Michigan growers using micro-rates for weed control are tracking GDD. A majority of these growers are basing their micro-rate timings on 225 GDD (base 34°F) while others are using other variations between 200 and 250 GDD depending on weed populations and soil types. By timing their micro-rate applications using GDD, many of these growers have been able to maintain good weed control, reduce sugar beet injury, and reduce the number of micro-rate trips across the field equating to reduced weed control costs. General recommendations for GDD micro-rate applications The first micro-rate application should be made when weeds are less than 1/8-inch tall. Normally, this occurs around 275 GDD with early emerging weed species like common lambsquarters; however this year we have noticed earlier common lambsquarters and velvetleaf emergence with the warmer temperatures, and in some cases, have had common lambsquarters ready to treat at 200 GDD. Therefore, it is important to start scouting for the first micro-rate application earlier this season. For the remainder of the micro-rate applications,
research from MSU has shown applying micro-rates on a 225 GDD schedule
has shown the most consistent weed control across species while
reducing the potential for sugar beet injury. However, in fields
with sandy or darker soils (high organic matter) and high weed pressures
it is suggested to check fields at 150 GDD and time applications
for 175 GDD. For growers who want to adjust the timing of micro-rates
relative to weed emergence it may be possible to lengthen the spray
interval early in the season (April) to 275 GDD when common lambsquarters
is the predominant weed. In May, this interval should be shortened
to 225 GDD until pigweeds (redroot pigweed and Powell amaranth)
start to emerge, then micro-rate applications should be made every
175 to 200 GDD. GDD calculations |
Records of manure applications |
On tile-drained fields: Please, keep records of manure applications on tile-drained lands. We have known instances of manure reaching tile lines and moving to surface waters. What we need are records of all the times that manure is spread on tile-drained fields and does not reach surface waters. The only way to verify this is if producers keep records of manure applications. On tile-drained fields, check the tile outlets before you spread and directly after you spread. If there is no change in tile outflow, or no flow at all, document this on paper. If you find that manure is moving to the tile lines, stop spreading immediately, contact the Pollution Emergency Alerting System 1-800-292-4706 and seek corrective actions. There is more concern for manure reaching tile lines when very dilute manure (often milk house wash-water) is applied at high rates. The current soil moisture conditions will also increase or decrease the chance of this occurring. Manure applications need to be done on a field-by-field basis and observe and evaluate the situation each day as weather conditions change. On non-tiled fields: Records are important to keep of any manure application on all fields. Record keeping is necessary to receive nuisance protection under the Right to Farm GAAMPs and will also improve your crop nutrient management. When the rate per acre of manure is know, the rate of nutrients can be calculated, fertilizer can be adjusted accordingly, money can be saved and environmental quality can be maintained. Several different record keeping formats are available at http://www.maeap.org/cnmp.htm including a version in Spanish. There is also a pocket-size notebook available by contacting MSUE’s Natalie Rector at 269-781-0908 or rector@msu.edu |
New Michigan law requires water use reporting for high capacity agricultural wells in 2004 |
P.A. 148 of 2003 - Water Use Reporting § The combined capacity of more than one well at a site that exceeds 100,000 gallons or more per day (greater than 70 gallons per minute), also meets the large capacity well definition. § Water use reporting will also include surface water withdraws with single or combined pump capacity of 100,000 gallons per day (70 gallons per minute). § These laws apply to all agricultural water uses (irrigation, hydro-cooling, on-farm crop processing/packing, animal watering, etc.). § Agricultural producers have the option of either reporting water usage to the MDEQ or the Michigan Department of Agriculture. There is a reporting fee of $100 for high capacity well owners to report to MDEQ, the fee is waived for agricultural producers who report to MDA. § Irrigators must decide which agency they plan to report by October 1, 2004 or they will be required to report to the MDEQ. Links are provided to each below. § Agricultural high capacity well owners need to begin keeping monthly water use records in 2004, and will be required to report water withdrawals in January of 2005. The MDA will assemble township-level reports each year and forward the information to the MDEQ. § Records must include the following: §
Amount of water used per month Water use reporting registration
links Go to the MDEQ Water Use Reporting Web Page at: http://www.michigan.gov/deq/0,1607,7-135-3313_3677_3704-72931--,00.html |
Regional reports1 - Southeast |
Commodity report If warm weather continues farmers will harvest alfalfa at or before May 20. Expectations are for a cold snap toward the end of April that may return spring crop development to a more normal pace. A few brave farmers as far north as southern Washtenaw County are putting corn in the ground. Farmers in more northern areas are taking advantage of dry soil conditions to complete tillage operations and prepare for corn and soybean planting. |
2 - Southwest |
Weather Commodity report The alfalfa is growing rapidly with the warmer temperatures.
Growth is between six to eight inches in height. Fields that I have
scouted do not show signs of alfalfa weevil feeding yet, but the
warm temperatures over the weekend will most certainly push their
development ahead. Watch for pinhole feeding symptoms on leaves
over the next couple of weeks. Corn planting has moved
into gear in some places in the southwest region. The eastern portion
of the region has begun planting commercial corn in earnest. The
western portion is beginning more slowly. Soil temperatures have
moderated to the mid to upper 50's following the warm temperatures. Soybean planting is just getting underway as well with very little progress at this point. Because of the expected smaller size of soybean seed this year, it might be a good idea to calibrate grain drills (see Calibrating drills for soybean production in this issue) this season to make sure that you are planting the intended population. Another thing that you may want to consider before you plant soybeans is to make sure that there is adequate potassium fertility in the soil. Research conducted during the 2003 field season indicated that the effect of soybean aphid feeding was more pronounced on fields where soil K fertility levels were low. |
3 - West Central |
Weather Commodity reports In grasses, orchard and brome are progressing nicely. Growth is at 5-7 inches. Some animals are out on pastures as hay supplies are mostly gone. Most fertilizer has been spread on wheat, weed control applied to many acres. Growth stages Feeke's 4-5. Stands look good. Most of acreage has been planted in oats. Some of the earliest planted has emerged. This is one of the best springs in recent past. Work is progressing nicely. If good weather continues, corn planting will start in earnest next week. |
4 - Central |
Weather Commodity reports Corn planting is just getting under way. Some growers have nearly half of their crop planted while others will get going next week. Many farmers are waiting for things to warm up some before planting. Planting of soybeans will begin next week. Alfalfa has begun to grow rapidly with the warm weather and rain over the past week. Several of last year summer seedings did not survive and were replanted. The spring seedings are beginning to emerge, and the stands look good at this time. In Isabella County record growing degree days for alfalfa and as of Monday, we have accumulated about 100. The early-planted oats have emerged and are doing very well. Stands are very good, and the alfalfa seeded with the oats is emerging nicely. The sugar beets are planted and some are beginning to emerge. The high winds over the past week have caused concerns. |
5 - Thumb |
Weather Commodity reports Planting of sugar beets is nearly complete. Emergence of early-planted fields is occurring. A concern with these emerged fields has been sustained strong winds that have caused some loss of stand and need for replanting. Limited areas of the Thumb received heavy rain just before record high temperatures, which caused some soil crusting. Very good field conditions have led to significant planting of corn. Increasing soil temperatures are showing promise for this early planted corn. Of course, there are still many questions about the chance for cold temperatures with the early planting timing. Some growers are concerned about limited soil moisture and are planting before they intended to in order to get the seed planted into adequate moisture. Plant growth of wheat continues to look good. Some fields are very nice with consistent growth while others are somewhat variable within the field. A couple of fields that I have scouted in Saginaw County are at Feekes growth stage 5. This advanced stage should create some scouting for weeds in wheat if chemical weed control is planned. |
6 - Northern Lower Peninsula |
Weather Commodity reports Wheat is looking very good. Greening up nicely, with very few bad spots in the fields. We should have a good year if it keeps up like this. Alfalfa has finally started greening up. It looks good in most spots to this point. Oats and barley have started going in. A few early fields are done. Potatoes are still waiting for some warmer weather. Still have a few more loads of spuds to clean out of storages. |
Spring has sprung |
The persistent troughing pattern across the Great Lakes region that brought cool, dry weather to much of the Great Lakes Region since late March finally broke during the past week. This resulted in an abnormally warm and unsettled weather pattern across Michigan. The unusually warm weather led to a surge in seasonal growing degree day accumulations and early overwintering crop development. Much needed rainfall eased dryness in northern sections of the state, but many southern areas remain abnormally dry. On Thursday morning (April 22), an area of low pressure was located across the southern Great Plains region. The low pressure is expected to move through the Ohio Valley during the next 24 hours, bringing an increase in cloudiness to southern sections of Michigan, and possibly some light showers or sprinkles, especially in the southern tier or two of counties in the Lower Peninsula. High pressure will move in behind the system with dry conditions expected Friday and Saturday. Temperatures will fall back to near or below normal levels for the season with highs the next few days generally remaining in the 50's and lows in the 30's. A hard frost is likely across Friday and Saturday mornings in northern sections of the state. Another low-pressure area will bring the chance for showers to the state once again by early Sunday continuing into early Monday. Tuesday and Wednesday are expected to be dry with a warming trend by the middle of next week. As of Thursday morning, two-inch soil temperatures had warmed to the mid-40's in northern sections of the state to the mid-50's across the south. Given cooler weather over the next several days, look for these temperatures to decrease a few degrees as well. Looking further ahead, medium-range forecast guidance suggests further changes of the upper air pattern across North America with the passage of another trough across the central and eastern U.S. in one to two weeks. The NOAA Climate Prediction Center 6-10 day and 8-14 day outlooks for April 27 through May 1 and April 29 through May 5 both call for a trough to be located over the Great Lakes region and a ridge over the western US, with warmer than normal conditions to the west of the region and cooler than normal temperatures to the east. For both forecast time frames in Michigan, this translates to an outlook of near normal temperatures for most of the state except for the western Upper Peninsula, where warmer than normal temperatures are expected. Precipitation totals for both periods are forecast to fall back to below normal levels statewide. Latest long lead outlooks During May, the outlook calls for increased odds of warmer than normal temperatures over much of the mid-Mississippi and Ohio Valley regions northward into southern sections of Michigan with the climatology scenario of equal odds elsewhere in the state. The warmer than normal forecast in sections of the Corn Belt region is due to drier than normal conditions and relatively low soil moisture conditions in this area presently as well as to long term climatological trends. Warmer than normal temperatures are also favored in the June-August time frame in southern and extreme western sections of the state with the equal odds scenario elsewhere. There is less in the way of direction for the precipitation outlook, with equal odds of above, below, and near normal levels forecast statewide for May and for all of the upcoming growing season. |