July 25, 2007
In this issue
§ European corn borer/ corn earworm update
§ Aster leafhopper numbers increase
§ Downy mildew update
§ Pocket scouting guide for potato diseases available
§ Regional reports
§ Weather
Next issue August 1
Beth Bishop
Entomology
Pheromone trap catches for European corn borer and corn
earworm continue to be very low. In most areas of
You can find current degree-day accumulations for your area by consulting the degree-day table in this issue of the Vegetable CAT Alert, or by accessing the MSU Enviro-weather website at http://www.enviroweather.msu.edu. Select the nearest weather station from the pull-down list at the top of the page, then click on “vegetables”. The first selection, “Weather Summary” will generate a table that includes degree-day data. Look in the degree-day base 50 column to find DD50 accumulations by date.
Since corn earworm (unlike European corn borers) cannot
survive the
Beth Bishop
Entomology
Scouts in
About two percent of aster leafhoppers collected from a
carrot field in
The number of aster leafhoppers present in celery and carrot
fields in
Currently, pyrethroids remain the best choice for controlling aster leafhoppers in celery and carrots. See Bulletin E-312, 2007 Insect, disease and nematode control for commercial vegetables insecticides registered for carrots and celery. You can find this bulletin online at http://web4.msue.msu.edu/veginfo/E312.
Mary Hausbeck
Plant Pathology
Since last week’s Vegetable
CAT Alert, downy mildew has been confirmed on cucumber at three new sites,
Fungicide recommendations remain the same.
§ Fungicides should be applied to cucumbers every FIVE (5) to SEVEN (7) days.
§ Fungicides should be applied to pumpkins, melons, cantaloupes, squash, zucchini and gourds every SEVEN (7) to TEN (10) days.
|
Applied before disease (7-day intervals) |
Applied after disease (5-day intervals) |
|
— Gavel 75WG (5 day PHI) |
— Previcur Flex 6SC (2 day PHI) |
|
— Previcur Flex 6SC (2 day PHI) |
— Ranman 3.6SC (0 day PHI) |
|
— Ranman 3.6SC (0 day PHI) |
— Tanos 50WG (3 day PHI) |
|
— Tanos 50WG (3 day PHI) |
|
|
Alternate products and mix each with either: — Dithane (mancozeb) 3 lb or — Bravo (chlorothalonil) 1.5 pt |
Alternate products and mix each with either: — Dithane (mancozeb) 3 lb or — Bravo (chlorothalonil) 2 pt |
Phillip Wharton and Willie Kirk
Plant Pathology
The new potato diseases scouting guide "A Pocket Guide
to Disease Scouting in Michigan Potatoes" is now available for purchase
from the MSU
Extension Bulletin office. This is a comprehensive pocket reference text
for use in disease scouting in
Ron Goldy
Temperatures during the week were generally below average (83oF) with highs of 73o to 85oF and lows from 51o to 65oF. The area received from 1.0 to 3.5 inches of much needed precipitation providing a brief slow down in irrigation activity with systems back to running full speed. Cooler temperatures have brought a much needed slow down for harvest activity.
Sweet corn harvest continues. European corn borer activity seems lower than normal this year.
Tomato harvest from all types continues. Volume has increased as more fields come into production. Pepper harvest has slowed primarily due to current low prices. Some sunscald has shown up on harvested fields and some blossom end rot is also evident. Eggplant harvest should begin soon.
Yellow squash, zucchini, cantaloupe and cucumber harvest continues with no problems. Early fields of cucumbers and squash are being removed and made ready for a second planting. Pumpkins are runnering, flowering and setting fruit, with some fruit soft-ball size. Watermelon is sizing well and harvest is expected to begin within two weeks. Squash vine borer trap counts have dropped to 4 per trap down from 24 last week. Virus levels remain low with only an occasional plant and fruit from the field being identified with symptoms. All stages of squash bugs can be found.
Bill Steenwyk
Temperatures were a bit cooler this past week, but the
unending dry spell continues. Parts of Van Buren County received a half to one
inch of rain. Farther north, in central
Insect and disease pressures in most crops are low. The main variables now are whether or not the fields are irrigated and how frequently. Fields receiving consistent irrigation are doing well. In non-irrigated fields, soil texture, structure and compaction dictates plant-available water and, accordingly, crop welfare. Despite the increased cost of supplying all that water, some farmers report that the reduced need for disease control measures more than offsets those costs. The occasional field has severe weed pressure. In this period of water deficit, competition from weeds is especially detrimental.
On muck soils, celery is being harvested. Reported yields range from good to moderate. The last of the transplants are now, or will soon be in the fields. In some fields where the early crop was harvested, a second planting has been established. Aster leafhopper numbers remain low, with some reporting populations somewhat higher than before.
Onion and leek appear to be doing well. Even the considerable acreage of non-irrigated onions continues their development. Some of the earliest plantings are lying down. Red beets are looking good, with harvest continuing. New radish plantings are growing where an earlier crop was harvested.
On upland soils, cucumber harvest is underway. I found a few fields with small infestations of bacterial wilt.
Melons, zucchini, and squash are developing well where irrigated.
Large portions of non-irrigated fields show severe drought stress. Cabbage development continues well unless the grower hasn't been able to keep up with water needs.
Tomatoes and peppers are developing normally.
Sweet corn is perhaps, the most variable crop. Irrigated corn is developing normally and the early harvest is quite good. Some non-irrigated fields however are a complete failure. Other fields have poor tip fill or inconsistent maturity. Blackbird feeding is a major problem in some areas.
Norm Myers
Drought has returned to our area with only a couple of hundredths of an inch of rain in the last ten days. Irrigation is once more running flat out where it is available.
This year’s crop of asparagus fern does not look that good, with generally small size and relatively few stalks per crown even after the rains we received on or before July 4. Tom-Cast sensors in full-season fields are now mostly at or near the 15 disease severity value trigger for the first purple spot spray. Rust and common asparagus beetle are also still active.
In carrots, Disease Severity Values have also jumped greatly. While there is probably some alternaria blight active, Mary Hausbeck’s technician Brian Cortright did identify some of the disease symptoms we are seeing as bacterial blight. Carrots are wilting badly where irrigation is not available.
Zucchini harvest continues for processing, but prices for fresh zucchini are so poor that most of that is being diverted to processing. I have seen no viruses yet, and with the dry weather phytophthora is also not an issue.
In winter squash and pumpkins, scouts report some alternaria lesions, but no signs of any other diseases including powdery mildew yet.
In sweet corn, I caught no corn earworm or European corn borer moths in my traps for the second week in a row.
Snap beans’ late planting is now emerged and looks good so far.
Jim Breinling
Rainfall amounts over the
past two weeks have been 0.85 inch at both the Ludington and Fremont MAWN
stations. Rainfall during the last 10 days however has been less than 0.10 inch
in the area. Daytime temperatures have been moderate to slightly below normal
along with cool nighttime temperatures. Although irrigation systems are going
strong, the favorable temperatures have helped to reduce crop stress.
The carrot crop in
Onions continue to grow well
and are beginning to bulb. Thrips can be found, but control has been
manageable.
Plant growth and maturity in pepper
fields is variable due to wind damage in June. Peppers are beginning to set and
some fruit is one inch in diameter at this time.
Slicing cucumber harvest is in
full swing. Growers are protecting this crop with sprays for downy mildew.
Winter squash plantings generally are
doing well, but vine growth is less than normal and wilting is common due to
lack of moisture even where irrigated. Bee activity and fruit set appears good
with some butternut squash 8 to 10 inches in length at this time.
Snap bean fields planted early in
July continue to do well, but moisture will be needed soon where irrigation is
not available. European corn borer counts this week at the
Sweet corn harvest has started in
Hannah Stevens
Much cooler temperatures over the past two weeks (a high of
85oF and lows ranging from 51-60oF) has felt more comfortable,
but in
Harvest of early sweet
corn is beginning this week bringing with it the opening of farm markets
for produce. The quality is variable but, by and large, clean and excellent
considering the dry conditions. European corn borer trap catches for the past
two weeks remain about the same as they have been in
Summer squash harvest continues. Incidents of virus are few so far this season.
Muskmelon harvest is beginning this week. Watermelon harvest will begin in a few days.
Tomato picking is beginning. While I would expect to see more blossom end rot on the first fruits, it seems to be limited. Growers must be doing an excellent job with consistent irrigation.
Fall crops such as broccoli transplants continue to be set.
Pollinators are more abundant than I have ever seen them in any and all flowering plants, cultivated and wild. Their humming may be heard from a distance in floriferous crops such as soybeans, and this morning five to six could be seen in each male pumpkin blossom.
Paul Marks
Warm and very dry weather this last week has increased the
stress on most crops and increased the cost of production on irrigated crops. The
saving grace has been the cooler temperatures, especially the nights in the
very low 50’s. For the month of July, according to the MSU MAWN station in
Sweet corn harvest is now in full swing with growers packing a nice crop from fields that have been irrigated, and lower quality from non-irrigated fields. Corn borer and corn earworm activity has been very low.
Tomatoes for fresh market are just getting started with good quality fruits being packed. Disease pressure is low from fungal pathogens, but bacterial diseases have marked some fruits.
Processing tomatoes for early harvest appear to have good fruit loads, but vines are much smaller than in recent years. Some blossom end rot is evident. Later maturing varieties are now just beginning to show fruit.
Vine crops have tolerated the dry conditions well, but are now showing stress in lower fruit numbers and size. Pumpkins are just beginning to set fruits. Downy mildew in our area is still limited to cucumbers, with the exception of one home garden of melons. Pollination has not been a problem as the bees, perhaps lower in numbers this year, have been able to work every day and all day with no rain to slow them down.
Peppers are being harvested for fresh market with nice size and quality bells now being marketed. Banana peppers for processing are just beginning to be harvested this week. Plant sizes in both crops appear to be smaller than normal.
Potatoes for fresh market are being harvested and packed, although still quite green. Tuber size is good from irrigated fields, but will be smaller from fields that lack irrigation, where vines are now maturing due to lack of moisture. Leafhopper numbers have been very low the last several weeks.
Jeff
Andresen
Agricultural Meteorology
Geography
An upper air ridging feature anchored across the Great
Plains region led to yet another abnormally dry week last week across most of
In general, weather forecast guidance for the next couple of
weeks does not suggest any major changes that would lead to meaningful relief
from the dryness. A weak upper air trough will move from the upper
Further ahead, a cool front is forecast to move through the
state Friday, which will bring the best chances for rainfall during the
upcoming week. Showers and thunderstorms will be possible in northwestern
sections of the state overnight Thursday, and across the
A broad ridging jet stream pattern is projected across the