Christmas trees
Field crops
Fruit
Home and yard
Nursery and landscape
Turfgrass
Vegetable
Diagnostic Services
Soil/Plant Nutrient Lab
Enviro-weather
Regional IPM Center
Pesticide safety
Organic: New Ag Network
Invasive species
Sustainable ag & food systems
MSU ANR departments
MSU Extension
Site index
Contacts/permissions
| Vegetable Crop Advisory Team Alert newsletter | |||||||||||||||||||||||
|
|||||||||||||||||||||||
 |
|||||||||||||||||||||||
| Vol. 22, No. 10, June 27, 2007 |
|||||||||||||||||||||||
In this issue  Pheromone trap update Squash vine borer and squash bugs Watch for thrips on cabbage Statewide downy mildew sprays recommended Too bad for cucumber growers! Regional Reports Weather |
|
||||||||||||||||||||||
|
|||||||||||||||||||||||
| Pheromone trap update The numbers of European corn borer moths caught in pheromone traps were low again last week in most locations except for the site in Macomb County. Sweet corn growers with corn about to tassel should check their fields for corn borer larvae. When tassels emerge, these larvae move down the stalk to the developing ears. If 20 percent or more of the whorls have larvae or feeding damage, apply insecticides to the whorl four days or less before tassel emergence. Consult Bulletin E-312, 2007 Insect, disease and nematode control for commercial vegetable insecticides registered for control European corn borer in sweet corn. You can find this bulletin online at http://web4.msue.msu.edu/veginfo/E312. Egg laying continues. Sweet corn with ears should be treated preventatively to avoid infestation. European corn borer moths caught in pheromone traps in different Michigan locations from June 19 to June 26
Only a few corn earworm moths were caught in pheromone traps. In general, we have not had weather conditions that are conducive to insect migration from the south. |
|||||||||||||||||||||||
| back to top |
|||||||||||||||||||||||
| Squash vine borer and squash bugs Squash vine borer adults and squash bugs have been reported on vine crops in Southeastern Michigan (view images). Squash vine borer moths are day-flying moths with a 1.0 to 1.5 inch wingspan. In flight, they look like wasps. There is one generation each year and adults emerge in late June/early July. They lay eggs at the base of squash plants, and upon hatching, larvae bore into stems (where they are protected from insecticides). Unless you scout fields for evidence of eggs or larvae, the first sign of squash vine borer infestation can be wilting vines in July and August. By that time, it is too late to do anything. Growers should scout their pumpkin and squash fields weekly for squash vine borer from late June through early August. Examine the base of vines for evidence of larval feeding (sawdust-like frass near entrance holes) and then split open the stem to confirm the presence of larvae, which suggests more eggs are being laid. Two insecticide sprays, ideally applied to the base of the plants, and timed five to seven days apart, will control newly hatching larvae before they are able to bore into the stem. Consult Bulletin E-312, 2007 Insect, disease and nematode control for commercial vegetables insecticides registered for control squash vine borer on your crop. Squash bugs are serious pests of pumpkins and squash. Both adults and nymphs feed by inserting their beak and sucking juices from plant tissue. Large populations can cause partial wilting, and later in the season, squash bugs may feed on the fruit, causing them to collapse or become unmarketable. Adults are 0.5 to 0.75 of an inch long, flattened and grayish-brown. Wingless nymphs are similar in appearance to adults, and are whitish when small, with a brown head, and grayish white when larger. Eggs are laid in clusters usually on the underside of leaves and are orange when first laid, but turn bronze-colored before they hatch. Squash bugs are virtually impossible to control later in the season when nymphs are large and the canopy is dense. The key to preventing squash bug problems is early detection and control of small nymphs. Growers should scout their field regularly for evidence of squash bug adults and eggs. Insecticides may be warranted if squash bugs are causing wilting of young plants (wilting is observed and squash bugs are present on the underside of leaves). Just before flowering, fields should be scouted for egg masses. This is the critical time to control squash bugs. If more than one egg mass per plant is found, an insecticide application is needed. |
||||||||||||
| back to top |
||||||||||||
| Watch for thrips on cabbage Thrips are reported in cabbage fields. Thrips populations can build up rapidly in hot, dry weather. Be aware that the Bt materials (Dipel, etc.) applied for control of “worms” are not effective against thrips. Consult Bulletin E-312, 2007 Insect, disease and nematode control for commercial vegetables insecticides registered for control thrips on cabbage. |
||||||||||||
| back to top |
||||||||||||
| Statewide downy mildew sprays recommended Downy mildew fungicide sprays should be applied to all cucumbers in the state immediately! Fungicides should be applied to cucumbers every five to seven days. Pumpkins, melons, cantaloupes, squash, zucchini and gourds should also be protected with downy mildew fungicides. Fungicides to these crops should be applied every 7 to 10 days. Table 1. Recommended products for managing downy mildew on cucumber and all cucurbits.
Use fungicides proven to work on cucumbers in Michigan! Over the last two years, many fungicide trials have been conducted in Michigan to determine the most effective spray programs. If you use only the recommended downy mildew fungicides at the prescribed spray interval, you will be protected from this potentially devastating disease. Do not use products that are not on this list based on promises from sales staff. Downy mildew confirmed in Michigan Downy mildew on cucumber was confirmed on June 25 in a homeowner’s garden in Monroe County. This garden has since been destroyed. There is also a suspect downy mildew case in Monroe County with a commercial cucumber grower. In this case, downy mildew fungicides had not been applied to this field. I will have a sample from this field late today for confirmation. These cases appear to be the result of relatively new infections that have become established within the last 7-10 days. A weather event may be responsible for the nearly simultaneous downy mildew outbreaks in Michigan, Ohio and upstate New York. In the latest spore trap readings, the downy mildew counts have taken a jump in at least one county. Additional counts are pending and this information will be made available on the downy mildew website associated with my homepage. If you suspect downy mildew please have it confirmed either through my lab (517)355-4576 or through Dr. Jan Byrne at MSU Diagnostics (517)355-3504. To better understand this downy mildew, my laboratory is collecting diseased plants for further analysis. If a sample cannot be sent to the lab, please call and arrangements will be made to pick it up. |
||||||||||||
| back to top |
||||||||||||
| Too bad for cucumber growers! Late on June 25, Paul Marks and Jennie Stanger visited a home gardener who felt his cucumbers were showing the same symptoms as last year when an unprecedented outbreak of downy mildew swept across the county in midsummer, killing nearly all home garden cucumber plants and many farm field plantings within several days. Unfortunately, he was correct and this may be the first confirmed outbreak in Michigan for 2007. It is not always fun to be first, and we will not identify the gardener even though he deserves credit for recognizing the symptoms and alerting MSU Extension so we can inform others. Commercial growers were already taking preventive measures because the disease had been reported this month in Canada and Ohio. Most are following MSU recommendations to use at least 3 fungicides in a rotation, two at a time, every three to five days. Their large spray equipment can distribute the chemicals in a very uniform mist to cover plant leaves with protection. The chemicals inhibit fungus spores that land on the leaves from germinating, or penetrating the leaf with their threadlike hyphae. Once the fungus is inside the leaf, it quickly damages cells and uses the plant nutrients to reproduce itself. Small bumps like miniature pimples form on the underside of the leaf, and erupt, releasing millions of tiny spores that blow like dust in the wind to other leaves, plants and fields. Paul Marks’ three photos show the yellowish spots first visible on the topside of leaves, the dirty look at the bottom side of those spots from all the tiny black spores forming, and the declining health of an infested plant (view photos). The reason growers must spray often is that the cucumber plants are quickly forming new leaves, and the reason for rotating chemicals is that the disease would otherwise develop resistance to one product used all the time. Furthermore, this disease is so different from the “normal” cucumber diseases like common powdery mildew, that at least two different fungicides must be used. It is not economical nor convenient for home gardeners to attempt chemical control. In fact, it is expensive and difficult for commercial growers as well. This one disease has potential to ruin the entire pickle industry in Michigan, which has been the number one state for that crop in recent years. It will affect the farmers, the laborers who often hand pick cucumbers in exchange for half the crop, the workers in pickle factories, and eventually, all of us. Last year some people blamed the first farm in the county where the disease was found, thinking that because the cucumber plants on that farm were early and large due to plastic and row covers, that perhaps the disease had been brought to that farm on plants from the south. However, this year, after learning of downy mildew reports from year-round cucumber production greenhouses in Canada, and looking at weather patterns and other outbreaks in Ohio, suspicion runs high that the disease is overwintering in those greenhouses. The need for extra ventilation of such greenhouses when weather warms up would spew disease spores into the air where wind could distribute them to our area early in the season, long before they would typically reach us from southern growers’ fields. Home gardeners around Michigan may get a few cucumbers before their plants succumb, and their best hope is that either the disease will be controlled at its source, or that resistant varieties will be found. Such studies are under way, and if you can tell us at the end of the season that the variety you planted remained disease-free and productive until late summer, we will pass on that information! |
||||||||||||
| back to top |
||||||||||||
| 2 -- Grand Rapids Area Bill Steenwyk Weather Conditions have been hot, with most areas receiving no significant rain for at least eight days. Northern Ottawa, Kent, and Ionia counties are significantly drier than the central areas and farther South into Barry, Allegan and Van Buren. Parts of Southern Ottawa and Kent counties have received welcome showers this morning. Irrigators are working hard to keep up. Non-irrigated crops are stressed and losing yield potential. Maintaining good weed control during times of moisture stress is very important. Crop reports Celery continues to look good, with early harvests approaching. Some onion and leek fields have been pressured by thrips. Cabbage harvest continues, with the crop looking good overall. The success of newer transplants depends on the ability to maintain adequate irrigation. Irrigated tomatoes, peppers and vine crops appear to be developing well. Many sweet corn fields look good overall. Stewart’s bacterial wilt is limiting the potential of some fields. One field, otherwise vigorous, shows substantial corn smut tumors in the leaf tissue. No European corn borer moths were found in the three pheromone traps. |
||||||||||||
| back to top |
||||||||||||
| 3 -- Oceana County Norm Myers Weather Our area hasn’t seen any rain since last week’s report. Irrigation is once again going at full tilt, especially now that the hot, humid weather has returned. Last week’s rain did make all of our crops jump in height, but are also at the point of needing another rain or un-irrigated crops could begin to go backwards. Crop reports There are a couple of growers still picking some fresh asparagus, but in general fields have been let go to fern for the season. Purple spot is a common problem in younger fields, partly I think, because of all of the damage from blown sand that we experienced earlier. I have not seen any final numbers for 2007’s crop, but I am sure it is significantly down from last year. Carrots benefited greatly from last week’s storm and the cooler weather that followed. Growers are irrigating furiously again, however. Tom-Cast sensors are launched, but haven’t been read yet. Very few aster leafhoppers reported as of yet. Winter squash and pumpkins are advancing nicely, with no reports of virus yet. However, most of these fields are not irrigated and will begin to suffer drought stress pretty quickly. Most zucchini fields are now planted. So far, we have had very few pest problems. In sweet corn, earliest planted fields are in tassel. I only caught two European corn borers and no corn earworm this week. Snap beans growers have begun planting the late snap bean crop. Where irrigation is not available, the beans are being planted in to dry soil. |
||||||||||||
| back to top |
||||||||||||
| 4 -- Mason-Newaygo counties Jim Breinling Weather Rainfall of 0.06 inch on Thursday June 21 is all that was reported at both the Ludington and Fremont MAWN stations during the past week. Daytime high temperatures at the Ludington station nearer to Lake Michigan were generally in the high seventies, while at Fremont to the south and east daytime highs were in the low to mid eighties. Soil moisture conditions in most of Mason County are still adequate, but it is different in Newaygo County where irrigation systems are running at full capacity and rainfall is very much needed. Crop reports Uneven growth can be seen in some carrot fields due to dry conditions and wind damage to foliage. Aster leafhopper counts continue to remain low. In pepper fields, wind damage has become more evident and in some spots has resulted in plant loss. Harvest of spinach has started, the warm temperatures and dry conditions have resulted in some acres not being harvested. Planting of snap bean acreage will be heavy during the next two weeks. Soil moisture will be needed in some areas for planting and germination. The European corn borer counts at the Mason County site were 0-0-0 again this week. First planting of sweet corn in Mason County are now in tassel. Plantings of hard winter squash are growing nicely, and some fields are starting to run, in these fields sidedress nitrogen has been applied. |
||||||||||||
| back to top |
||||||||||||
| 5 -- Macomb, St. Clair and Lapeer counties Hannah Stevens Weather and crop conditions It is precariously dry in this area, and while drip irrigated vegetable crops are doing well, those such as sweet corn are showing stress. A humid 94oF yesterday was the high for the week, but wind is an issue in high evapo-transpiration rates. I am hoping for a shower today. Crop reports In sweet corn, European corn borer flight continues to be troublingly high with an average of 34 moths per trap and reports of heavy infestation of small worms in the emerging tassels. The plants are under drought stress, and this combination with the high temperatures are not an ideal spray situation. Otherwise the crop is making rapid progress in this heat. In winter squash, Phytophthora blight has been confirmed in a field on plastic and drip irrigation. Isolated plants are affected. Summer squash, including zucchini and yellow squash, are approaching harvestable yield. Several plants exhibiting virus symptoms have been seen. (see photo 1) Muskmelons and watermelon fruit are sizing at a remarkable rate, from walnut size to football size in a week. Tomatoes are setting fruit, and the first set appears to be of good quality. A case of distorted foliage was traceable to glyphosate drift. (see photo 2) New potatoes are now available at local farmers’ markets. (see photo 3) The lettuce crop, both wholesale and retail, continues to be harvested and is of good quality and yield. As of last week, aster leafhopper pressure was low and aster yellows not a problem, The carrot and onion crop on muck soils was in excellent shape last week, but rain is needed. |
||||||||||||
| back to top |
||||||||||||
| 6 -- Monroe County Paul Marks Weather Hot and dry has been our situation for the last seven days in our area. Most farms are in need of rain and irrigation systems are all running. Estimated potential evapotranspiration for this last week has been more normal, at approximately one quarter of an inch per day, allowing irrigation to at least catch up with the need on most farms. Crop reports Sweet corn is in full silk in early fields, and at first harvest in smaller isolated plantings that were under tunnels. Corn borer traps this week averaged less than one moth per trap for the second week in a row with low moth pressure. However, even fields that were treated regularly during the higher moth flights three and four weeks ago have some worms present. Tomatoes have made very good growth during this warm weather and appear to be very disease free at this point. Early fruits in market tomatoes also appear to be of good quality, although first harvest is a week or so away in earliest plantings. Cucumbers in our area are now showing the first indications of downy mildew with confirmations in both one home garden and one commercial field. These two infestations are more than 15 miles apart! Neither of these infested plantings had been protected with recommended fungicides. I have not seen any symptoms of this disease in any treated fields. Larger vine crops such as hard squash and pumpkins are now beginning to vine with some fields having very poor stands as a result of our hard rainfall the week after they were planted. Some replanting has been done this last week. This week, I have seen both squash vine borer moths and squash bug egg masses in pumpkin fields. Potatoes continue to look good, although stressed for moisture in a number of fields at a poor time (tuber bulking), where irrigation has not been able to keep up with need. Leafhoppers continue to pressure this crop, and while controlled with insecticides, reinfest some fields within two weeks. No disease found in this crop so far this season. Cabbage harvest is now rolling along at full steam. I have seen several fields this week with thrip feeding just below the outer wrapper leaves. Other worms have not been a problem in our area. |
||||||||||||
| back to top |
||||||||||||
| Weather news Jeff Andresen Agricultural Meteorology Geography Following another entire week without significant rain, a weak- and slow-moving cool front will move west to east across Michigan Wednesday, June 27, bringing the chance for showers and thunderstorms and some much-needed moisture. Given that dynamics with the system are weak, rainfall totals will be limited in most areas to 0.25-0.50 inch or less, and some areas may remain dry. Best chances for rainfall with this system will be across southern sections of the state. After the front clears the state, cooler and drier weather is likely statewide by late Thursday continuing through the upcoming weekend as Canadian-origin high pressure moves into the region from the north. Temperatures will fall back to near or below normal levels by Thursday, with highs ranging from the upper 60's or low 70's far north to near 80 south and low temperatures from the 40's north to low 60's south through Sunday. As mentioned here last week, medium range forecast guidance is suggesting the formation of an upper air trough across the eastern United States next week with northwesterly flow across Michigan and the Great Lakes region. Unfortunately for those needing rainfall following the drier than normal trend in place since early June, both 6-10 day and 8-14 day outlooks covering July 2-8 and July 4-10, call for normal to below normal precipitation totals. On the brighter side, temperatures are expected to be cooler, which should reduce water use rates. Mean temperatures across the state are forecast to remain at near normal levels statewide during the 6-10 day time frame, while below normal temperatures are expected state- and region-wide during the 8-14 day period. New long lead outlooks Earlier this year, sea surface temperatures in the equatorial Pacific region were falling and the development of an El Niño event looked possible. That surface temperatures trend unexpectedly stabilized during the spring season and has remained steady since, reducing the chance of an El Niño anytime soon. ENSO factors thus play little if any role in the new series of NOAA long lead outlooks for the upcoming months. For the month of July, the outlooks are directionless for Michigan and the Upper Midwest, with near equal chances for below-, near-, and above normal mean temperatures and precipitation. During July, warmer than normal temperatures are expected across eastern and western sections of the United States. Cooler and wetter than normal weather is expected to continue (due to abnormally wet soils) from the central Corn Belt region south- and westward to Texas. During the 3-month (July-September) period, the outlooks suggests warmer than normal temperatures Michigan, with the equal odds scenario for precipitation. Warmer than normal temperatures are also forecast for the upcoming fall season as well. |
||||||||||||
|
Email the web developer.