A Newsletter for Commercial Growers of Fruit and Vegetable Crops
"We are what we repeatedly do. Excellence, then, is not an act, but a habit." --Aristotle
Address any questions or comments regarding this newsletter to the individual authors listed after each article or to its editor, Rick Weinzierl, 217-333-6651, email@example.com. To receive email notification of new postings of this newsletter, call or write the same number or address.
In This Issue:
Upcoming Programs (Organic Apple Field Day, Southwestern IL Vegetable Twilight Meeting [corrected date is August 13, 2008], Pumpkin Field Day))
Regional Updates (from Elizabeth Wahle and Maurice Ogutu)
Notes from Chris Doll (crop and pest phenology, leaf analysis, application timing for Retain, peach crop estimates, weed control)
Fruit Production and Pest Management (phenology updates on oriental fruit moth and codling moth)
Vegetable Production and Pest Management (managing tomato diseases)
From southwestern Illinois ... Elizabeth Wahle is away from the office on contractual leave, but she asked that this issue contain a correction on the date for the twilight meeting for tomato and sweet corn growers (the editor's error, not hers) ... this program is scheduled for August 13, 2008, at Fournie Farms in Collinsville. The meeting will begin at 6:00 pm. Fournie Farms is located between I-255 and IL-157 just off Horseshoe Lake Road. From I-255 take Exit 26. Take a left on to Horseshoe Lake Road. Go approximately ½ mile; Fournie Farms is on the left. For those taking I-70/55, take Exit 11. Take a left at the light onto IL-157/Bluff Road. Make a left on to Horseshoe Lake Road. Go approximately ¾ mile; Fournie Farms is on the right. For those using MapQuest, the physical address is Fournie Farms, Inc., 925 McDonough Lake Rd, Collinsville, IL. For more information, contact Elizabeth Wahle, 618-692-9434 or firstname.lastname@example.org.
In northern Illinois, we've had sunny days with average temperatures in the upper 80s to low 90s and night temperatures in the upper 60s to low 70s recently – so yes, very hot and humid, especially with temperatures over 90 in Chicago metropolitan area. Soil moisture content has reached very low levels in some areas, particularly near Kankakee, where less than 0.2 inches of rainfall was recorded during the last two weeks and many growers are irrigating their vegetable fields. Other areas received 1 to 3 inches of rain, with the highest amount recorded on July 12 and 19. Rainfall amounts of more than 4 inches were recorded in northern counties bordering Wisconsin, particularly in Rockford and surrounding areas.
Apples are sizing well, and orchardists are continuing with summer spray programs, and it is time to include calcium sprays. Sour cherry harvesting is going on in many orchards, and orchardists are encouraged to check leaves for cherry leaf spot infection. Japanese beetle populations have increased during the last two weeks, and they are feeding on fruit and vegetable leaves, causing serious damage on sour cherry, raspberry, and grapes. Summer-bearing raspberry and blueberry harvesting is also going on in many farms in the region.
Tomato and pepper fruits are sizing well. Pumpkins and winter squash are starting to vine out in the northern parts of the region. In the Kankakee area, spaces between pumpkin rows are filled with vines. Squash vine borer and cucumber beetle adults are flying in pumpkin and squash fields, so growers are advised to scout and control these insects as needed. Imported cabbage worm adults were observed flying in cole crop fields, and Colorado potato beetles are feeding on eggplant and potato leaves. Corn earworm counts have been low, but growers need to check traps daily when the sweet corn crop is silking. In the Kankakee area, harvesting of sweet corn commenced last week, and picking of cucumbers, summer squash, green beans, and cabbage is going on as well. There were reports of angular leaf spot on muskmelons and bacterial spot on pepper leaves.
Maurice Ogutu (708-352-0109; email@example.com)
Some of the rain that ran off a couple of months ago would be appreciated now that summer temperatures have arrived. A week of 90+ temperatures takes out a lot of soil moisture and also has pushed fruit crops forward a little. Peach harvest and apple development are seven to nine days behind many of the recent years, and that makes it seem like a late harvest. Some Red Havens have been picked, but most are still firm. Color and size look good. Pristine apples are ready for harvest, and Galas are showing some change toward maturity too. Triple Crown blackberries are being picked, but Chesters remain behind.
Degree-day accumulations presented below for weather stations in the Illinois State Water Survey WARM data base have been summarized using the Degree-Day Calculator on the University of Illinois IPM site (http://www.ipm.illinois.edu/degreedays/index.html). The list for 18 locations includes only degree-day accumulations and projections based on a 50-degree F developmental threshold and a January 1 starting date, but other options that use different thresholds and specific biofix dates are available on the Degree-Day Calculator. The degree-day calculator is available as a result of a joint effort of current and former extension entomologists (primarily Kelly Cook) and Bob Scott of the Illinois State Water Survey. If you have questions about how to use the site, contact me or Bob Scott (firstname.lastname@example.org).
Oriental fruit moth and codling moth phenology updates
(Yes, the text here and the tables below are similar in format to what has been in previous issues. The numbers are up-to-date, however, so be sure to look over the details for you location if you grow apples and/or peaches. )
Biofix dates for first flights of oriental fruit moth (OFM) are presented in the table below, along with degree-day (DD) accumulations based on a threshold of 45 degrees F. Generations begin to blur as the season progresses, but the earliest of third generation moths began flying at around 1900 degree days, base 45F, and that flight will continue over the next 2 to 4 weeks. Over the last 2 weeks traps in our "network" in the far south and at Urbana have continued to catch relatively low numbers of moths (with a little increase recently at Urbana), but as always, growers are advised to rely on data from traps in their own orchards. Check the June 10, 2008 issue of this newsletter for comments on making OFM control decisions based on degree-day accumulations.
Biofix dates for codling moth at six Illinois locations are listed in the table below, along with degree-day accumulations (base 50F) and projections for weather stations near each location.
Developmental events for the codling moth based on degree-day accumulations are presented below. Remember that "biofix" refers to the date of the first sustained capture of first-generation moths in traps.
(Table based on Orchard Pest Management by Beers et al., published by Good Fruit Grower, Yakima, WA.)
Rick Weinzierl (217-244-2126; email@example.com)
Managing Tomato Diseases: Septoria Leaf Blight, Early Blight, and Bacterial Diseases
Septoria leaf blight (Septoria lycopersici), early blight (Alternaria solani), bacterial canker (Corynebacterium michiganense pv. michiganense), bacterial spot (Xanthomonas campesiris pv. vesicatoria), and bacterial speck (Pseudomonas syringae pv. tomato) have been observed in many commercial fields and home gardens in Illinois in the past two weeks. You need to take apply all effective measures to manage these diseases; otherwise, crop losses could be substantial. Management of these diseases should be through preventive practices rather than eradicant approaches.
Septoria Leaf Blight. Septoria leaf spot usually appear on lower leaves after the first fruit sets. Lesions also appear on stems, petioles, and the calyx. Spots are circular, 1/16 to 1/5 inch in diameter, with dark brown margins and tan to gray centers dotted with the fruiting bodies (pycnidia) of the pathogen. A narrow yellow halo is often associated with leaf lesions. The disease spreads upward from oldest to youngest growth. If the leaf lesions are numerous, the infected leaf may turn to yellow and then brown, and then wither. Fruit infection is rare.
Early Blight. Early blight occurs on leaves, stems, and fruit. The disease appears first on older leaves as small brownish black lesions. The tissue surrounding a spot may become yellow, and when spotting is abundant the entire leaf may become yellow. The spots enlarge rapidly, and by the time they are ¼-inch in diameter or larger, concentric rings may be distinguished in the dark brownish portion of the spot. Affected plants may become defoliated, exposing the fruit to sunscald. The fruit becomes infected, generally through the calyx or stem attachment, in either the green or ripe stage. The fruit lesions attain considerable size, occasionally involving the entire fruit, and usually have concentric rings. The diseased areas appear leathery and may be covered by a velvety mass of black spores.
Management of Septoria leaf spot and early blight. Management strategies for Septoria leaf spot and early blight include the following practices: planting resistant cultivars wherever available; disposing of crop refuse after harvest by plowing under; controlling weeds in and around the field; crop rotation with non-host crops (e.g., cereals) for 3 years or longer; minimizing wetness period of plants by adjusting timing of irrigation; staking plants to improve air circulation; keeping workers and equipment out of fields with wet foliage; and applications of effective fungicides every 7 to 10 days or more often when weather is warm and wet. Several effective fungicides [Amistar, Cabrio, chlorothalonil (Bravo, Echo, Equus), Endura (early blight), Flint, Gavel, Quadris, Reason, Scala (early blight), and Ziram] are available for control of Septoria leaf spot and early blight of tomato.
Bacterial Canker. Infected seedlings may be quickly killed. The early symptoms of the disease on the foliage are wilting, curling of leaflets, and browning of leaves. Foliage infected with the canker pathogen has distinct black leaf edges with no spotting on the interior of the leaves. Sometimes a thin yellow border is present between the dead leaf margins and healthy tissue. As the leaves die, the petioles remain green and firmly attached to the stem. A cut through the stem shows yellowish brown discoloration of the vascular element. Fruit symptoms may be observed at any age but are usually seen first on green fruit 1/2-2 inches in diameter. White spots 1/8 inch in diameter develop on the fruit. The spots have a dark brown center, which becomes raised, and are surrounded by a distinct white halo; they have been termed "bird's-eye spots."
Bacterial Spot. Leaves, stems, and fruit may be infected. Infected leaves show small, irregular, dark lesions, which can coalesce and cause the leaves to develop a general yellowing. Fruit lesions are initiated only on green fruit. The lesions begin as minute, slightly raised blisters. As a spot increases in size it becomes brown, scab-like, and slightly raised. These spots enlarge up to 1/8 to 1/4 inch in diameter. Although ripe fruits are not susceptible, lesions are very obvious if fruits were infected when green.
Bacterial Speck. Infected leaves develop small, black lesions, often with a discrete yellow halo. Infected fruits develop lesions, which are small, sunken, black spots surrounded by darker green haloes. On ripe fruit, spots are dark brown to black, superficial flecks. The symptoms of bacterial spot and bacterial speck are similar. These two diseases are more readily distinguished on the basis of fruit symptoms.
Management of Bacterial Diseases. For managing bacterial diseases of tomatoes, the following recommendations should be practiced: (1) use only certified, pathogen-free seed; (2) plant only certified, disease-free transplants; (3) in the greenhouse, seedbeds and soil must be sterilized; (4) practice 2- to 3-year crop rotation with non-solanaceous crops; (5) follow good sanitation programs; (6) in the field, control irrigation to minimize plant wetness; (7) control the weeds; and (8) chemical application, including sprays of fixed copper (e.g., Kocide-3000, Cuprofix Disperss) can help in protecting healthy plants against these bacterial diseases. Application of Tanos (famoxadone + cymoxanil) suppress development of all three bacterial diseases of tomato. Also, application of Actigard (acibenzolar-s-methyl) can result in effective control of the bacterial spot and bacterial speck.
For more information on chemical control of tomato diseases in commercial fields, consult the Midwest Vegetable Production Guide for Commercial Growers (http://www.btny.purdue.edu/Pubs/ID/ID-56/).
Mohammad Babadoost (217-333-1523; firstname.lastname@example.org)
Less seriously ...
Is it possible to characterize nonliving things as male or female? Let's give it a try ...
(And yes, in the copy I received for this entry there were a lot more objects that were characterized as female, but I'm not about stir up even more trouble.)
University of Illinois Extension Specialists in Fruit and Vegetable Production & Pest Management
Integrated Pest Management
College of Agricultural, Consumer and Environmental Sciences
Crop Sciences | Entomology
Natural Resources & Environmental Sciences
Illinois Natural History Survey
Illinois Fruit and Vegetable News
Copyright © 2004 University of Illinois at Urbana-Champaign