In Michigan, downy mildew on cucumbers remains limited to Monroe County. On June 29, a downy mildew outbreak on cucumbers was reported in southern Ontario. Information is being gathered to learn more about this latest report. Recent weather conditions have not been favorable for downy mildew spread in the north and west portions of Michigan. Many cucumber and cantaloupe growers have continued to keep a protective spray on their fields. Conditions in southeast Michigan will require that growers maintain a tight fungicide program. As long as no new fields develop the downy mildew in Michigan, growers outside of the southeast region of the state may lengthen their spray intervals by a couple of days. The strongest fungicide program includes Previcur Flex (+ Mancozeb or Bravo) alternated with Tanos (+ Mancozeb or Bravo) Note: See the June 14 issue of the Vegetable CAT Alert for 2005 trial results. A program of Mancozeb alone can also be used but carries a higher risk of downy mildew disease. Growers using Mancozeb alone should be ready to switch to a stronger fungicide program that includes Previcur Flex (+ Mancozeb or Bravo) alternated with Tanos (+ Mancozeb or Bravo) if downy mildew is detected in their region. We are still handling cucumber samples with any suspicious disease symptoms. Last week, Alternaria was confirmed on pickling cucumber leaves from both Allegan and Monroe Counties. Both fields were close to harvest (see pictures).

Cercospora on carrots has been noted in several fields. It seems that early July is often the beginning of foliar disease. Studies over the years clearly show that fungicide sprays must be initiated at the very first trace of disease in the field. Playing catch-up with fungicide sprays once foliar blight is established is difficult. The frequent rains in some areas of the state have resulted in accumulation of the Disease Severity Values for those growers spraying according to the Tom-Cast forecasting system.

Powdery mildew on vine crops has not been reported in the state. However, fields should be scouted at least once per week. I’ve been concerned because I’ve seen fairly large plants of cucumbers and pumpkins in the garden centers loaded with powdery mildew. If powdery mildew becomes established in homeowner’s gardens, field outbreaks won’t be too far behind.

The number of European corn borer moths caught in pheromone traps are very low throughout most of lower Michigan. An average of 0.7 moths per trap were caught in Ingham County, 0.7 in Oceana County and none were caught in Monroe County during the period of June 27 to July 4. An average of 16 per trap were caught in Mason County. Although high, this number is down considerably from the trap catch last week. In the southern part of the Lower Peninsula, the first adult flight is over, and it is nearing the end in the north. The risk of European corn borer infestation is low throughout most of Michigan, but vulnerable crops (sweet corn with ears and peppers and snap beans with fruit) should still be protected.

Corn earworm was once again caught in pheromone traps in Ingham County (5 per trap). Sweet corn in silk is especially vulnerable to corn earworm infestation. Insecticide sprays should be directed to ensure thorough coverage of the silks. Recent weather patterns were conducive for insect migration into the state, and we may see larger populations of corn earworms in coming weeks.

Aster leafhopper numbers were moderate in celery and carrot fields during the last week in June. Infectivity rates remain relatively low. MSU Diagnostic Services has recently tested populations from the following sites for aster yellows:

There is an error in Bulletin E-312, 2006 Insect, Disease and Nematode Control for Commercial Vegetables. The insecticide, Actara® (Syngenta ), is not registered for use on vine crops (cucumbers, squash, pumpkins, melons) as is reported in the bulletin. Please make this correction to your copy. This bulletin can be viewed at http://veginfo.msu.edu.

Regional reports
1 -- Southwest
Ron Goldy

Weather
Temperatures through the period averaged near normal with highs between 74°F to 92°F and lows from 49°F to 66°F. The area has received only 0.35 inches with most occurring on Monday (July 03). The rain total since June 8 is 0.46 inches so soil moisture levels continue low in many areas and irrigation is necessary. Unirrigated plantings are suffering from lack of moisture as well as lack of available nitrogen.

Commodity reports
Sweet corn harvest has begun from early-planted, row-covered fields.

Watermelon and cantaloupe are blooming at levels that bees find attractive so growers should be sure to have hives in these fields.

Cucumber harvest volume has greatly increased over the past week.

There was some wind damage that occurred over the weekend in yellow squash and zucchini fields.

Pumpkins are close to tip over. No squash vine borer has been reported at this time.

Tomatoes, peppers and eggplant continue to grow well in response to temperature and light levels. Peppers are blooming, and plants are large enough that ties are going in.

Dry weather has kept disease levels low. Insect numbers also appear low at this time.

2 -- Grand Rapids Area
Amy Irish-Brown

Weather
Air temperatures have been normal to slightly above normal for the past week. Degree day totals continue to run about 8 days ahead of normal. There has been little rain across the region over the past week, and soils are getting quite dry. Irrigation is needed in many locations.

Staking and tying continues in tomatoes. Plants look healthy with no noticeable foliar diseases yet.

Radish planting and harvest continues.

Lettuce crops are in various stages of growth. The predicted cooler weather will be good for lettuce crops.

Cabbage transplants are doing well.

Celery is developing nicely. Soils are getting very dry and irrigation is needed. Leafhoppers need to be monitored to prevent the spread of aster yellows.

Early planted sweet corn is in tassel. Corn borer larvae can be found in some areas and control measures are needed. Corn earworm will also be a concern on any sweet corn that is in tassel. Be sure to cover the entire plant, including the silks, when making insecticide applications for corn borers and earworm.

Seeded vine crops are beginning to run. Squash vine borers are just beginning to fly, so management applications should be made this week. Striped cucumber beetles can be found in many fields, and insecticides may be needed to prevent disease spread.

4 -- Mason-Newaygo counties
Jim Breinling

Weather
Temperatures held fairly normal during the past week with higher humidity until a cool front passed through the area following scattered thunderstorms the morning of July 4.

Rainfall amounts in the area were light and scattered during the week with 0.35 inch reported at the Ludington MAWN station and 0.25 inch at the Fremont station. The large thunderstorm cell in Northern Mason County late Saturday night (July 1) did not result in any large rainfall amounts, reports were in the 0.25 inch range. With only 0.48 inch recorded during the last 13 days at the Fremont MAWN station, irrigation systems are operating in vegetable fields in Newaygo County.

Snap bean planting continues this week in Mason County with favorable soil moisture and planting conditions. European corn borer trap counts on July 3 were 12, 3 and 40. The one moth caught in the corn earworm trap does not appear to be corn earworm.

Vine crop plantings on July 3 vary in plant growth, color and uniformity. Spots in fields were lost due to standing water but no loss (wilting plants) due to phytophthora is evident at this time. Some fields are being sprayed for control of stripped cucumber beetle where control from soil insecticides at planting has been reduced due to heavy rains after planting. Cultivation and hoeing is being done at this time in many fields for weed control.

6 -- Monroe County
Paul Marks

Weather
Accumulated GDD50 for our area this week total 1146, which is just a little below the long term normal of 1185 putting us about two calendar days behind normal. Potential evapotranspiration this week only reached 0.2 inches on two days. Rain over the last week has been sporadic with some growers receiving more than three inches and others less than one inch. Soil moisture in most fields is high enough that irrigation is not needed.

Commodity reports
Sweet corn planted in open fields will begin to be harvested by the end of this week with larger volumes available early next week. Corn borer and earworm traps were all empty this week. Corn borer larva are still difficult to find and very little feeding damage is evident in corn.

Tomatoes for fresh market are just beginning to be harvested with reasonable quality fruits for the first harvest. Larger volume will be available next week. Bacterial canker has been found in several fields that were hit with hail several weeks ago even though copper sprays were applied as soon as possible after the damage.

Slicing cucumbers are being harvested from earliest plantings in open fields without tunnels. Larger volume will be in the market next week. Hard harvest pickles are beginning to vine. I have not seen any additional fields with downy mildew.

Muskmelons planted under tunnels have fruits developing up to six inches while open planted fields have plants running off the plastic mulch and heavy with female flowers. Vines look very good.

Pumpkin and hard squash are beginning to vine. Stands look very good in these crops. Weed seedlings are becoming a problem under vines as a result of our abundant rain since this crop was planted, even though herbicides were applied.

Cabbage harvest is continuing at a rapid pace. Thrips have been found in several fields this week, which is not too much of a surprise now that small grains and grasses are maturing. Worm pressure in cabbage has not been serious so far this season.

Potatoes in our area range from being vine killed for early harvest next week, to just being hilled in later planted fields. Leafhopper numbers are running wild in small plantings that have not been sprayed, to under control in commercial fields that have had as many as three insecticide applications.

A large area of Canadian-origin high pressure will dominate weather across the Great Lakes region for the remainder of the work-week with fair and mostly dry weather expected into the upcoming weekend. Temperatures will remain at or below the climatological normals through Thursday (July 6) and then warm to above normal levels by Friday as the center of the high pressure shifts eastward and allows warmer back into the region on southwesterly winds. An upper air disturbance will bring the chance for some scattered showers and thunderstorms to northern sections of the state by Saturday and Sunday, although most areas will remain dry. A cool front is expected to move through the region by late Sunday or Monday and provide the next best chance for significant precipitation. High temperatures will generally range from the upper 70s north to low 80s south on Thursday, warming to the low to mid-80s over most locations by Friday into the weekend. Low temperatures will generally range from the upper 40s north to the mid-50s south Thursday increasing to the 60s by Saturday and Sunday.

Medium range forecast guidance suggests upper air troughing over the western United States with a ridge over most of the central United States. The NWS Climate Prediction Center 6-10 day and 8-14 day outlooks (covering July 10-14 and 12-18) both call for above normal temperatures. Precipitation totals during the 6-10 day time frame are forecast to remain at near normal levels. During the 8-14 day period, the center of the ridge is forecast to edge closer to Michigan, and the outlook calls for precipitation totals to range from near normal levels in eastern sections of the Lower Peninsula to below normal levels over the Upper Peninsula and western Lower Michigan.

As of early July, soil moisture levels across the state range from excessive to abnormally low thanks to a highly variable rainfall pattern since early April. Figure 1 depicts precipitation departures from normal across the state during the past 90 days based on a combination of observed station reports and NEXRAD radar precipitation estimates. Departures range from more than 6 inches above normal in west central and central sections of Lower Michigan to more than 6 inches below normal in western sections of Upper Michigan (see Figure 1). For climatological perspective, normal accumulated rainfall for this period ranges from just less than 8.0 inches over northeastern sections of the state to more than 10.0 inches over the southwestern Lower and western Upper Peninsulas. Based on the short and medium-range outlooks, the precipitation and soil moisture deficits in some western sections of the state are a growing concern, especially over western Upper Michigan.