The first flight of European corn borer moths is occurring in most of south and central Michigan. An average of 78 moths per trap was caught in pheromone traps in Monroe County during the week of May 31 to June 6. At a second site in Monroe County, an average of 23 moths was caught. We caught 13 moths per trap on the MSU campus in Ingham County; 6 moths per trap were caught in Montcalm County, 11 moths per trap were caught in Macomb County and less than 1 moth per trap was caught in Oceana County.

Corn borer egg masses have been found in sweet corn fields, and these will hatch soon. European corn borer moths start to lay eggs around 450 to 500 GDD50. Most sweet corn, peppers and snap beans are not at a vulnerable growth stage for corn borer damage. (Sweet corn is vulnerable at tassel and beyond, snap beans and peppers are vulnerable after flowering begins.) Corn borers may lay eggs in potato fields if sweet corn is small and unattractive. See the May 31 Vegetable CAT Alert for more details.

Large numbers of adult striped cucumber beetles have been reported feeding on young vine crops. The mild winter plus the recent heat and moisture have resulted in a high population of overwintered beetles. Cucumber beetles can severely damage or kill young plants. They also transmit bacterial wilt disease through their feeding. Cucumbers, melons, processing pumpkins, butternut squash and hubbard squash are susceptible to bacterial wilt.

At-plant treatments are most effective at controlling cucumber beetles and are recommended in areas where beetle numbers are expected to be high. A number of foliar insecticides also protect against cucumber beetle and should be applied when adult numbers exceed 0.1 to 1 beetle per plant (the smaller the plant, the lower the treatment threshold). See Bulletin E-312, 2006 Insect, Disease and Nematode Control for Commercial Vegetables, for insecticides registered to control insect pests on various vegetable crops. This bulletin can be viewed at http://veginfo.msu.edu.

Aster leafhoppers collected from carrot and celery fields at five sites in Michigan were tested for aster yellows infection by Diagnostic Services. Leafhoppers collected from celery fields in eastern Allegan County and southern Van Buren County did not test positive for aster yellows. The treatment threshold for celery in these areas is 35 leafhoppers per 100 sweeps. At one site in northwestern Allegan County, approximately 5% of the leafhoppers tested positive for aster yellows. This translates into a treatment threshold of 7 leafhoppers per 100 sweeps for celery and 10 per 100 sweeps for carrots.

In Oceana and Mason counties, 3 to 10 percent of the leafhoppers tested positive for aster yellows. Treatment thresholds for carrots in these areas are 5 to 10 leafhoppers per 100 sweeps for carrots.

The following is an article written by Dr. Chris DiFonzo, field crops entomologist, for the Field Crop CAT Alert. The article discusses details of a multi-state soybean aphid trapping network.

Why should vegetable growers care about this network? In previous years, large numbers of soybean aphids taking flight from soybean fields in late July and early August are thought to have spread viruses to a variety of vegetable crops (including vine crops, snap beans and peppers). Soybean aphids, like other aphid species, find new fields by flying, landing and “tasting” plants with their mouthparts and then flying on if the plant is not to their liking. During this “tasting” behavior, plant viruses are both acquired and spread. The “tasting” (and consequent virus spread) occurs so quickly that insecticides have no impact on virus transmission. But, by being aware of the timing and size of the aphid flight in late July and August, growers can avoid planting virus susceptible varieties when aphid flight is high. The web site given in the article (http://www.ncipmc.org/traps/) shows up-to-date aphid trap catch numbers for the (soon to be) five locations in Michigan.

Northcentral Regional Aphid Suction Trap Network was turned on last week in at least eight states. As in 2005, Michigan has three trapping locations that cover a north-south transect: MSUs Saginaw Valley Bean and Beet Research Farm in Saginaw County; the MSU Entomology Farm in Ingham County; and the Kellogg Biological Station in Kalamazoo County. By the end of June, we will set up two new locations, one at the MSU Extension Office in Monroe County to cover southeast Michigan and another in western Michigan in Oceana County. Monroe County has a high population of buckthorn, the overwintering host for soybean aphid; it experienced heavy, early aphid infestation in 2005, and thus may benefit from trapping information. The location in Oceana County is specifically targeted to provide information to vegetable growers in Western Michigan, where soybean aphid is implicated in virus spread.

The traps suck in migrating insects, including winged aphids, flying over 20 feet above the ground. The insects end up in a jar of antifreeze just above the fan in the base of the trap. Sample bottles are changed weekly, and mailed to the University of Illinois where aphids are removed, identified and counted. The soybean aphid counts are posted on a web site, http://www.ncipmc.org/traps/, where you can view individual traps from each of the eight states. There are currently 33 traps on the network, plus five to six more that will come on line in June.

Later in the season, in late July and early August, increases in flight often time with peak infestations in soybean fields. For example, last season (see the 2005 data at http://www.ncipmc.org/traps), tremendous numbers of soybean aphid were trapped in early to mid-August, when aphid populations peaked in nearby fields. Such heavy aphid flights increase the risk of reinfestation in previously-sprayed fields we certainly experienced that frustrating situation in 2005.

In the last four years, heavy aphid flights in late July to early August coincided with virus infection in vegetable crops in Michigan. The suction traps can alert growers to a potential virus threat and may eventually help vegetable growers make decisions about late-plantings, for example, variety selection.

At the end of the season, the suction traps play their most important role, potentially predicting next year’s soybean population. Suction traps catch the winged males and females that leave soybean and go back to buckthorn, where soybean aphid overwinters.

In Illinois, the number of fall migrants caught in suction traps correctly predicted the next year’s aphid population (outbreak versus no outbreak) in four out of four seasons, including 2005. The 2005 season was the first year for the Regional network, across eight states. At the end of 2005, some areas (such as Michigan) had low fall trap catches; others (for example Minnesota) had high fall flights. June 2006 is a critical test for the predictability of the traps in theory, Michigan should have low colonization this spring, and Minnesota should have early, heavier colonization. Stayed tuned!

Regional reports
1 -- Southwest
Ron Goldy

Weather
Temperatures through the period were near normal with highs ranging from 71°F to 83°F and lows from 45°F to 58°F. Soil temperatures are averaging in the low 70s. The area received between 0.4 to 1.6 inches of rain in the early hours of June 7. The amount depended on where the thunderstorms tracked. Some areas are still in need of rain.

Commodity reports
Many asparagus fields will be finishing this week, and growers will be applying herbicides by the weekend.

Non-tunneled tomatoes are being staked and tied.

Pepper plantings have greatly improved the past week and new growth is beginning.

Tunnel-grown vine crops are in bloom and growers have moved in bees. Cucumber beetle populations are seemingly under control.

Potatoes are in bloom.

Sweet corn is in the 6 to 8 leaf stage and has greened-up nicely in response to warmer temperatures.

2 -- Grand Rapids Area
Amy Irish-Brown

Weather
Air temperatures have been much closer to normal the past week – quite a change from early last week when we had daily highs above 90°F for two days. We’ve moved back ahead of normal on degree day accumulations and are running about a week ahead of normal averages for degree accumulations of all bases. Rains across the region have been variable. There has been some more scattered hail in the Grand Rapids area over the past week.

Radish planting continues, as does harvest.

Lettuces on muck soils are in various stages of growth and harvest.

Sweet corn continues to emerge with some early planted fields at 6 inches or so. Additional planting continues.

Vine crop seeding and transplanting continues. Growth has been good with all the heat last week.

Asparagus harvest continues. Picking was difficult last week with all the hot weather, and growers were having difficulty filling orders over the Memorial Day weekend. But the more normal temperatures lately and some rains have helped spear production and picking continues.

Tomato transplanting continues. Growth is good due to high heat levels.

3 -- Oceana County
Norm Myers

Weather
Oceana County experienced widespread rain last evening and overnight. I had almost an inch in my gauge this morning, but the automated weather station at the Asparagus Research Farm reported only a third of an inch over night. We had adequate soil moisture before the rain, but this rain is still welcome.

In carrots, cover crops have almost all been sprayed off and growers are trying to deal with some difficult weed problems generated by all of the rain. Aster leafhopper numbers are highly variable.

Planting of hard squashes and pumpkins is nearly finished. Hard winter squash acreage is down, but pumpkin acreage is up enough to make up for it. This rain should be ideal for activating residual herbicides on these crops.

Some early processing zucchini were planted last week, but most of the processing and fresh crop will go in next week.

Early crops of snap beans are emerging and growers are reporting potato leafhoppers moving from first cutting alfalfa on to snap beans. My European corn borer traps only had two moths.

4 -- Mason-Newaygo counties
Jim Breinling

Weather
Temperatures have been in the normal range during the last seven days. Precipitation amounts have been the topic of interest in the area ranging from very localized heavy amounts to no rainfall to general rainfall overnight on June 6-7. Heavy rainfall in Mason County Memorial weekend resulted in some extremely wet soil conditions causing localized crop loss and delayed planting. Thunderstorms the afternoon of June 2 in eastern Newaygo County resulted in hard rains in short time periods. Thunderstorms also repeated during the afternoon of June 3 in Newaygo County. Hail damage in some fields due to these storms ranged from light to severe.

Commodity Reports
First carrot plantings are well established and now 6 to 8 inches tall. Root development is beginning. Planting completed on June 6. Sites for the aster leafhopper testing program have been selected and were sampled this past week.

Onion growth in the early planted fields is now at fourth leaf.

Spinach harvest began last week in southern Michigan. Hail damage occurred in the fields in Newaygo County.

The planting of winter squash was delayed this past week in Mason County due to wet soil conditions. Large numbers of cucumber beetles were reported in cucurbit plantings immediately after emergence and/or on newly set transplants.

Snap bean planting continues in the area. The first European corn borer trap counts on June 6 averaged 9 per trap. Moths were sent to MSU for confirmation.

5 -- Macomb, St. Clair and Lapeer counties
Hannah Stevens

I observe and continue to hear of seedlings on black plastic (melon, peppers) damaged by heat. As the May 31 article on the topic discussed, contact of the tender young stem with the hot plastic can cause injury. The bright sun is resulting in very high temperatures under plastic, and many row covers are being removed.

A variety of leaf lettuces as well as romaine have been at farmers markets for the past 10 days or so. Spring onions and snap peas are also at markets.

Broccoli picking is also underway but the heat is shortening this early spring harvest.

First picking of baby squash on plastic and under row covers should begin on Friday for retail markets.

Tomatoes stakes are being set.

Pumpkin seeding continues with seedling emergence in many areas. Transplanted pumpkins may be suffering in some areas from wind damage.

6 -- Monroe County
Paul Marks

Weather
Most of our area received no rain during the last seven days; however, very scattered showers in small isolated areas provided up to one quarter of an inch but also brought some hail causing some damage. Accumulated GDD50 are now at a total of 628 for the season – just two calendar days ahead of the long-term normal for this time of the year.

Commodity reports
Sweet corn has made very good growth with adequate moisture and warm nights. European corn borer adult moths in traps this week averaged 78 per trap, down 50 percent from last week. This week I have found the first ECB eggs of the season (Photo 1) but no larva yet.

Tomatoes are flowering in early market fields with fruits up to 2 inches in earliest plantings. Processing fields are more than 80 percent planted with good growth in early planted fields. No problems so far in this crop other than a few potato beetles.

Cabbage has made great growth with early fields now about a week from harvest. Insect pressure in this crop is very low considering all of the imported cabbage worm adults that have been in the fields.

Pepper transplanting is nearly complete with some fields planted over Memorial Day weekend showing stem damage from soil heat (Photo 2) even where no plastic mulch was used.

Potatoes in our area have a very wide range of development from still not emerged in late fields to blooming and small tuber development in early fields.

Pumpkin planting has just begun.

A cool front will slowly move from west to east across Michigan Wednesday (June 7), bringing a good chance for showers and thunderstorms to much of the state. Best chances for rainfall will be across eastern sections of the state, while many western areas will remain dry. Behind the front, look for dry and cooler weather Thursday continuing through Saturday. Temperatures during the next several days will fall back to below normal levels. High temperatures will range from the 60s far north to the 70s south Thursday through Saturday. Low temperatures will range from the low 40s north to the 50s south during the same time frame. Slightly warmer temperatures are likely by early next week. The next chance for rainfall will come late Sunday or Monday with a chance for scattered showers and thunderstorms across the state.

In the medium‑range, forecast guidance is suggesting split stream jet stream flow across western North America joining into a strong, single stream feature across the northern Great Plains and Great Lakes regions. This pattern would lead to a relatively active storm track along the United States/Canadian border.

Earlier this year, meteorologists at Accu-Weather, a commercial meteorological firm in Pennsylvania, released an extended outlook that mentioned the possible return of “Dust-Bowl” type conditions to portions of the central United States. The Dust-Bowl era of the 1930s (especially 1934 and 1936) included some of the most severe heat and drought conditions experienced in the central United States during the last century. Many of the climatological records in Michigan for extreme maximum temperatures, including the state’s all-time high temperature of 112 EF at Mio (July 13, 1936), were set in the 1930s.

The rationale for the outlook is associated with unusually warm sea surface temperatures over portions of the northwestern Atlantic Basin (The same warm waters that helped fuel a record number of tropical storms and hurricanes last summer and fall.) and relatively cool water in the eastern Pacific. These anomalous sea surface conditions were also thought to be in place during the 1930s and are thought to be associated with a westward shift of the low-level jet stream (from just above the surface up to about 4,000 feet). The low-level jet stream is critical as to precipitation climatology across the Great Plains region as it acts to transport large quantities of Gulf of Mexico-origin moisture (the major “raw material” of precipitation) northwestward into the region.

Under the current scenario, the low-level jet stream would shift westward and flow more frequently over sections of arid Mexico (instead of the Gulf), reducing the amount of water transport into the United States and to less precipitation. There is another related issue referred to as an atmospheric “feedback” mechanism. When the earth’s surface is relatively well-watered (i.e. frequent precipitation), a significant amount of incoming solar energy goes into evaporating water (This can account for more than half of the total incident solar radiation.). If there is less water to evaporate (i.e. low rainfall), a larger fraction of the incoming solar energy goes directly into heating the ground surface and the air above it, leading to relatively higher air temperatures. In addition, a portion of the water that falls as precipitation in the Great Plains is of local origin (The evaporation took place recently within a few hundred miles.), a phenomenon referred to as “precipitation recycling.” Therefore, prolonged drought can also reduce the amount of water available for future precipitation, which lends some scientific foundation to the old saying, “drought begets drought.”

Overall in this case, the forecasters believe that a reduction in regional precipitation over an extended period (months or years) will lead to a drier, warmer landscape. So does this mean that we will be looking at scenes from the Grapes of Wrath across sections of the central United States anytime soon? Only time will tell. Drought conditions as depicted by NOAA’s Palmer Drought Index are currently reported across large areas of the Rocky Mountain and Great Plains regions and current long lead outlooks do suggest warmer than normal temperatures across large sections of the southern United States (The NOAA long lead forecasters take the dry soil feedback mechanism into account as well.).

One thing is certain. The extreme conditions of the 1930s did not materialize overnight. Many months and even years of anomalous weather were involved, and some of the conditions were associated with poor land management practices that do not exist (or are not allowed) today. It is also worth remembering a helpful old rule-of-thumb adage that I picked up as an undergraduate meteorology student: Never forecast a new record. There is truth to this adage as climatological records represent the most extreme events observed, which means their probability of occurring is extremely small. Hopefully, that will remain true in this case as well.