Illinois Fruit and Vegetable News:

A Newsletter for Commercial Growers of Fruit and Vegetable Crops
A Publication of University of Illinois Extension and the College of Agricultural, Consumer, and Environmental Sciences

Vol. 9, No. 1, March 11, 2003

"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, weinzier@uiuc.edu. To receive email notification of new postings of this newsletter, call or write the same number or address.

This issue's words of wisdom ... which usually means the jokes ... are at the end of newsletter ... check the last page.

In this issue

Crop Reports (Notes from northern Illinois and the Dixon Springs Ag Center)

Notes from Chris Doll (Earliest pink in peaches and apples; Apogee; strawberry cultivars; facts and fiction)

New Registrations (Protegé fungicide and iron phosphate slug baits)

Fruit Production and Pest Management (Sprinkling for frost protection; pheromone traps for fruit insects; fire blight and peach leaf curl prevention)

Vegetable Production and Pest Management (Herbicides under plastic mulch; information network for corn earworm and corn borer trapping data)

University of Illinois Extension Specialists in Fruit & Vegetable Production & Pest Management

Crop Reports

In northern Illinois, winter conditions prevailed early this week, with temperatures less than 10 degrees F on Monday morning. The region had snowfall of more than 6 inches this month, and due to low temperatures, the ground is still covered with snow. We expect day temperatures to reach the lower 50s and night temperatures in upper 30s to lower 40s by the weekend. Soil moisture is very low, as rainfall of only about 1 inch has been recorded in the area from the beginning of the year, and less than ½ inch this month. Because it has been so cold, very few outdoor farm operations have been going on. It is time for dormant season sprays in orchards and pruning of grapes, brambles, blueberries, apples, peaches, pears, and other tree fruits.

Maurice Ogutu (708-352-0109; ogutu@uiuc.edu )

From the Dixon Springs Ag Center ...
Apple pruning is continuing with the hopes of being finished before the end of the week. We are also going to be pruning the blueberries as well as applying a fresh blanket of sawdust mulch around the plants. Row covers will be removed from the strawberry plasticulture field this week, and pre-emergent herbicide will be applied to knock out as many weeds as possible before they get started in the aisles. I think other growers in southern Illinois are going to be removing their row covers as well.

I would like to thank all of the participants (speakers, sponsors/exhibitors, and attendees) at the 2003 Illinois Small Fruit and Strawberry Schools for another successful year. The total attendance for both days was nearly 400, representing 8 states.

There is a website created by Dr. Barclay Poling from North Carolina State University that is a very good source of information for those interested or working with strawberry plasticulture. Although the site is geared for NC growers, there is a lot of information that Illinois growers may find beneficial. The address for the Berry Agent is http://intra.ces.ncsu.edu/depts/hort/berrydoc/.

Also from the 2003 Strawberry School, Dick Funt from Ohio State University gave an excellent presentation on strawberry frost control, including a very informative handout. Because the information in this handout was not included in the proceedings for the 2003 Illinois Small Fruit and Strawberry Schools, I've provided it under the "Fruit Production and Pest Management" heading of this issue of the newsletter.

Bronwyn Aly (618-695-2444; baly@uiuc.edu )

Notes from Chris Doll

Lots of folks thought that February was a long, cold and dark month ... and they were right. But for fruit growers and especially peach growers who prefer that flower development is slow until temperatures moderate, it hasn't been bad. At this time, there is a trace of bud swell on apricot, Japanese plum and blueberry. A few peach buds have been frozen, but the crop should be there as of today. From the records that I have kept at Edwardsville for 37 years, the earliest pink on peach was on 3/5/92, 3/9/74, and 3/14/90, and for apples it was 3/28/76, 3/28/91, and 3/30/00.

A convenient way to record the dates of plant development is to pen in the dates of occurrence on pages 48 and 49 of the "Commercial Tree Fruit Spray Guide". You may study these pages for potential killing temperatures, but I find them to be a good record from year to year, and also in diagnosing spray schedules that show only the spray date and not plant development.

The snowy southern areas should now be snow-free and activities can include brush removal, herbicide and fertilizer applications, and continued pruning. Peach growers should have 50% of their nitrogen applied while they await further crop development. Other tree fruits and small fruits can receive the full rate so that incorporation into the soil begins with the spring thaw and rains.

The fire blight epidemic that struck Illinois and Missouri growers in 2002 caused a resurgence of control discussions over the winter. Dr. Babadoost summarized the control procedures at the regional meetings, with the spray schedule based on the Maryblyte program as the best potential. The use of Apogee in this area was very limited last year, and a good evaluation of its effectiveness was not forthcoming. However, other areas report good results, and for this the product must be applied early - in full bloom to early petal fall. Use the full rate for the TRV. And according the MSU Management Guide, growth control is not concentration-dependent, or in other words, it can be applied either dilute or concentrate.

For the strawberry growers, the following varieties were rated high for Ohio by Dr. Richard Funt of OSU: Lester, Earliglow, Honeoye, Allstar and Jewell, with Ovation and Avalon as trial varieties. This was reported at last week's Strawberry School. Dr. John Masuinas reported that Sinbar herbicide is now labeled at 1-3 ounces per acre (on soils other than sand) after transplanting, but that if any plant growth has started at the time of application, immediate irrigation or rain of 3/4 inch of water is needed for washoff from the plant. Plasticulture growers reported that fall growth of plants was much less than a year ago but that little or no plant injury from low temperatures was seen. The protective row covers were on most of the plantings last week, but should be off by now.

A retiree's winter allows for thoughts about Fact and Fiction. Therefore, here are a few items that you may or not have seen as fruit growers:

• Dormant oil sprays may cause injury when applied at or near 32 degrees F .
• Never combine copper sulfate alone with oil.
• Avoid using Abound or Quadris to McIntosh or Gala apples.
• Pruning at or near 0 degrees will damage fruit trees.
• Never use sulfur on apple and peach trees at temps above 85 degrees.
• Sulfur and captan need a pre- and post-interval of 7, 10 or 14 days from oil.
• Always have the soluble bags of pesticides dissolved before adding boron to water in the spray tank.
• Lorsban should not be applied to sweet cherry tree foliage.
• Codling moth pheromone traps do not catch moths in all orchards.
• Wind chill has no effect on flower bud hardiness.

In HortTechnology, Vol 12, no.1, 2002, Tom Deckers and Hilde Schoofs reported that foliar applications of calcium for increasing apple quality and storability is a common practice in Belgium. Many formulations have been tested in the past 20 years, but none were superior to calcium chloride or calcium nitrate.

Chris Doll

New Registrations

Protegé (azoxystrobin) for control of seed and seed-borne diseases
Protegé (azoxystrobin) was recently registered for control of seed and seed-borne diseases. Manufactured by Syngenta, Protegé is a strobilurin fungicide with broad-spectrum activity. Protegé is a preventive seed treatment fungicide with systemic properties recommended for the control of several important plant diseases. It is registered for use to control seed-borne and soil-borne pathogens that cause seedling damping-off in sweet corn, cucurbits (cucumber), legume vegetables, and several field crops. Label information of Protegé is available at the following website: http://www.cdms.net/ldat/ld68D000.pdf

M. Babadoost (217-333-1523; babadoos@uiuc.edu)

Iron Phosphate Baits for Slug Control
Baits containing ingredients that are poisonous to slugs have long been used in slug control. Until recently, the only two active ingredients in commercial slug baits registered in the United States have been methiocarb and metaldehyde. Methiocarb, the active ingredient in Mesurol, is labeled for use only in nonfood crops and may not be used in strawberries. Metaldehyde is the active ingredient in many slugs baits that are labeled for use around food crops, including Deadline, Prozap, Cory's Slug and Snail Death, and many others. These baits are formulated as granules, pellets, or pastes, all meant to remain mostly intact through periods of wet weather. Labels on all metaldehyde baits specify that they should be applied to the soil surface near the plants to be protected; these baits are not to be applied directly to plants. In strawberries, they are most effective when they are applied before ripe strawberries are present, because although they are formulated to be attractive to foraging slugs, they will not "out-compete" ripe fruit well enough to divert hoards of the hungry molluscs.

A new slug bait recently registered in the United States and elsewhere around the world is iron phosphate. It is an attractive alternative to existing baits primarily because it is considered nontoxic to birds and mammals. Although metaldehyde baits are not highly toxic in comparison with many other insecticides, even their low toxicity has been linked to bird kills where birds fed directly on granules or pellets. Baits containing iron phosphate are sold under trade names including Sluggo, Escar-go, and Worry Free, as well as others. Recent trials conducted in Oregon found metaldehyde baits to be more effective than iron phosphate baits, but the new iron phosphate baits did provide some control. Iron phosphate baits are approved for use in Certified Organic production.

Rick Weinzierl (217-333-6651; weinzier@uiuc.edu )

Fruit Production and Pest Management

Sprinkling for Frost Protection of Low Growing Crops (information from a handout provided by Dick Funt of Ohio State University at the 2003 Illinois Small Fruit and Strawberry School)

Sprinkling for frost protection is effective for two reasons - (1) heat is released at the plant surface where it is most needed for protection and (2) the fluid involved is water, a readily available resource to many growers.

How does it work? When a blossom or fruit that is coated with liquid water begins to drop below 32°F, the freezing point of water, the water film begins to freeze, liberating heat of fusion. Sufficient heat is released to maintain a 32°F temperature at the interface between the water and the newly forming ice, even though the air temperature in the vicinity continues to fall. In fact one can count on the temperature of the interface between the water and the ice (water vapor being involved also, so the so-called triple point of water is achieved) being 32°F near sea level and very close to 32°F even a few thousand feet above sea level. The trick is to supply water at least as rapidly as it is being frozen to ice. However, freezing is not the only energy-transferring process that may take place when ice and liquid water are exposed to unsaturated air. Evaporation, an energy consuming process, also occurs. When equal amounts of water are evaporated as are frozen, 7 1/2 times as much energy is consumed as is liberated. In other words, if as little as 1/7 of the water evaporates as it freezes to ice, the process results in cooling and ceases to be a protection method. The amount of evaporation is controlled by air dryness and wind speed at the plant level. Fortunately, both decrease with decreasing height. Wind speed decreases near the soil level and the relative humidity increases. Therefore, sprinkled low-growing crops show less tendency to be harmed by evaporative cooling than taller-growing crops.

How much water is needed for protection? This answer remains poorly defined even though it is possible to estimate the amount of water needed for given wind, temperature, and humidity conditions. Lack of uniformity of coverage creates problems. Uniformity is poor to start with and becomes progressively worse with increasing wind drift. It is the coverage of the particular blossom of fruit that must be maintained at a minimum level.

One factor in coverage is rotation rate, a compromise between distance and frequency of wetting. In general, the rotation rate of the sprinkler head should be no less than 1 rpm.

A second factor in coverage relates to the uniform distribution of water around the sprinkler. Uniformity at the top of the plant canopy may be improved by increasing the overlap of patterns. Since low-growing crops have a shallow canopy depth, this also means that fairly good distribution will be maintained throughout the depth of the canopy.

Table 1 represents a relatively conservative estimate of the amount of water necessary for crop protection when the problem of distribution and other factors are considered.

When to start and stop? Low-growing crops cool more rapidly than does the air nearer eye level where we conventionally place thermometers. Therefore, it is recommended that unshielded minimum-indicating thermometers be placed on a narrow board in the horizontal plane at crop height. Do not be alarmed if evaporative cooling causes an initial drop in temperature of several degrees shortly after placement. This often will occur when the air is dry, but recovery to 32°F generally occurs in a matter of minutes.

Since each 0.10 acre-inch of water that is applied amounts to 2715 gallons, there is incentive to refrain from starting until absolutely necessary. Otherwise, soils may become water-logged before the frost season is over. Because the actual critical temperature for blossom and fruit loss of most crops is suspected to be about 4°F below 32°F, it is suggested that sprinkling can be withheld until temperatures in the canopy drop to 30°F. To cut the decision this closely, however, demands good temperature data taken from adequate numbers of thermometers exposed properly, and the use of nozzles which will rotate in below freezing weather.

Unless soil drainage is good, there is incentive to turn off the water as soon as possible. It may be turned off when the ice is melting and continues to melt after the water has been turned off. Damage from heavy ice accumulations normally is minimal on low-growing crops because they generally support themselves from the ground through pillars of ice.

Once the system is started, it is disastrous to stop until melting can be assured. Therefore, either a gravity system (storage pond, well above crop level ) must be employed or some auxiliary pumping equipment must be on standby which can be moved on line in a matter of minutes.

Unfortunately, sprinkling systems generally are designed to provide a fixed application rate so that regardless of the conditions, the maximum amount of water is applied. If a means of varying the application rate without disrupting the uniformity of the distribution can be developed, it would be a boon to this method.

References:

Braud, H. J. and P. L. Hawthorne. 1965. Cold protection for Louisiana strawberries. La. State Univ. Agr. Exp. Sta. Bul. 591. 44 pp.

Gerber, J. F. and J. D. Martsolf. 1965. Protecting citrus from cold damage. Univ. of Fla. Agr. Ext. Serv. Cir. 287. 29 pp.

Rogers, W. J. and H. L. Swift. 1970. Frost and the prevention of frost damage. USDC, NOAA, NWS Cir. 35 pp. (Available from Supt. of Documents, U. S. Govern. Printing Office, Wash., D. C. 20402 ).

Originally prepared by: J. D. Martsolf, Assoc. Professor of Agricultural Climatology, and P. A. Ferretti, Small Fruit and Vegetable Extension Specialist. The Pennsylvania State University, University Park, Pa. 16802.

Pheromone Traps for Fruit Insects
For apple, peach, and grape growers, NOW is the time to order pheromone traps for key insects if you've not already done so. Although traps are available and useful for monitoring many insects of fruit crops, the ones listed in the table that follows are probably the most important. Other pests that may be worth monitoring with traps include dogwood borer, spotted tentiform leafminer, redbanded leafroller, and obliquebanded leafroller in apples and peachtree borer in peaches. Contact me if you want more information on these insects.

What kind of traps should I use?

A few companies manufacture traps, and all have a similar range of designs. Trece is still the best known, so I'm using their models as examples, but there's no reason not to use other traps as long as they are pretty much identical in shape and size. The standard sticky trap for most orchard insects has been the Pherocon IC. The inside surface of the bottom - the "floor" of the trap - is coated with stickum or tanglefoot, and the bottom hangs from the top by wires. Spacers on the wires hold the bottom slightly below the top or roof so that there is an opening all along the sides as well as the ends of the IC trap. Although this trap has been used for monitoring flights of most orchard insects, a slightly different trap, Trece's Pherocon ICP, has been recommended most often for codling moth trapping. Although the trap top is the same as the one used for the IC, the bottom of the ICP trap is slightly smaller than the IC bottom, and it is attached without spacers so that it slides under the sides of the trap top, leaving a closed trap except for the ends. The ICP trap is the one I have used for several years to monitor codling moth flights around Illinois. Trece recently began selling a new trap, the Pherocon VI, and it differs from the other two described above primarily in that it's quick to set up (the user doesn't have to assemble the top and bottom with wires), and it uses a separate sticky bottom or "liner" that slides in and out. It's main benefit is that it is MUCH faster to change sticky liners on this trap than it is to change the bottoms of the IC or ICP. I compared these three traps at the University of Illinois orchard last year and found no difference in how many codling moths they captured over the season as a whole. The IC bottoms caught more extraneous things (insects and debris) than the other two, but otherwise there was no difference in their performance. I find the Pherocon VI to be so much easier and faster to handle than the others, so I recommend using it (or a similar trap from another manufacturer) for monitoring codling moth, Oriental fruit moth, grape berry moth, lesser peachtree borer, leafrollers, etc.

From left: Pherocon IC trap, Pherocon ICP trap, and Pherocon VI trap.

What attracts moths to traps?

For all the moths typically monitored using sticky pheromone traps, the trap must be baited with a pheromone lure - usually a small piece of rubber or plastic containing a synthetic blend of chemicals that is very similar to compounds used by female moths to attract males. When traps capture male moths, that serves as an indication that females are also present, and mating and egg-laying are occurring. When you order pheromone traps, you also must order lures for the specific insect(s) you wish to monitor. (Sometimes you may order "kits" that come with a combination of traps and enough extra sticky liners and lures to last the season.) Remember that although you may use the same type of trap to monitor different pests, you must use only a single lure per trap ... it does not work to put lures for codling moth and tufted apple bud moth in the same trap. Depending on the pest species, lures usually last 2 to 8 weeks, so you have to order enough lures to last through the whole season.

What about apple maggot?

For apple growers in the northern half of Illinois, monitoring the flight of apple maggot flies also is necessary. Traps for apple maggot flies rely on appearance (the color and shape of a bright red apple) and the use of a food odor ("apple volatiles") instead of a pheromone, and they are designed to capture female apple maggot flies ready to lay eggs on fruit. All the major suppliers of insect traps carry these kinds of traps. Growers should order the red spheres, tubes or tubs of stickum or tanglefoot, and the food lures recommended by the supplier. Apple maggot traps may be used without any food lures; counts are interpreted accordingly.

An apple maggot trap.

How many traps should I use?

There are no precise answers, but in general, for the moths that are pests in Midwest fruit crops, use 2 to 3 pheromone traps per pest species per each block of trees or vineyard up to 15 to 20 acres in size. Guidelines often recommend at least 3 traps for any orchard up to 15 acres in size and 1more trap for every 5 to 10 acres above 15. To monitor 50 acres of trees in 3 or 4 separate blocks, use at least 2 traps per block and at least 6 traps total. Always use at least 3 apple maggot traps (red spheres) per block of trees. See the table below regarding placement of traps.

If you have only one block of trees, you may want to order 3-trap "kits" that suppliers package for each of the major pests. Kits with "standard" lures will include 3 lures per trap, but because the lures for most will have to be replaced every 4 weeks. most Illinois growers will need yet another 2 extra lures per pest species per trap to get through the entire season. Suppliers also sell these extra lures and extra "liners" (the sticky trapping surface) for traps. If you operate an orchard larger than 20 to 30 acres, you'll need more traps; don't "mess with" 3-trap kits; contact the suppliers and make plans to order supplies in bulk. "Long-life" lures are available for the codling moth and the Oriental fruit moth (and some other species) ... these lures last 8 weeks between changes and are the best choice for almost all Illinois growers.

Apple growers in southern Illinois ... a few years ago we saw some problems with tufted apple bud moth in orchards treated pretty much exclusively with organophosphates. With greater reliance on alternative chemistries in recent years, this pest has not reached outbreak levels in any Illinois orchards in the last 2 years (to my knowledge), but I'm including it in the table below because it still warrants attention in some orchards.

Fire Blight and Peach Leaf Curl Control During Dormancy and Bloom
Fire Blight. Fire blight is the most important disease of apples in Illinois. It occurs every year and causes blossom blight, shoot blight, canker blight, and rootstock blight on apples and pears. To minimize the losses to fire blight, dormant copper spray and application of an antibiotic during bloom is recommended. Copper must be sprayed prior to or at silver tip. Copper should be applied to the entire orchard block, including non-susceptible cultivars. The reason for treating non-susceptible cultivars is that even normally fire blight-resistant trees can be colonized by the bacteria and serve as a source of infection during bloom. Several copper compounds can be used in the dormant sprays. If copper sulfate is used, it must be applied when trees are dormant. If copper sulfate is applied later than silver tip, plant injury can result. Also, do not apply copper sulfate with oil; apply copper sulfate and dormant oil as separate sprays spaced at least 10 days apart. Fixed coppers such as Kocide and C-O-C-S can be tank mixed with early season oil sprays. For more information, consult the "Illinois Commercial Tree Fruit Spray Guide 2003." Also, detailed information on fire blight can be found at the website:

http://www.ag.uiuc.edu/~vista/abstracts/a801.html .

Peach Leaf Curl. In 2002, an unprecedented incidence of peach leaf curl was observed in Illinois. To control leaf curl, peach and nectarine trees should be sprayed during the dormant season. Trees can be sprayed after leaves drop in the fall or before buds swell in spring. Chlorothalonil, carbamate, ziram, or copper compounds can be used for dormant spray to control peach leaf curl. For more information, consult the "Illinois Commercial Tree Fruit Spray Guide 2003." Also, more information on peach leaf curl is available at the website: http://www.ag.uiuc.edu/%7Evista/abstracts/a805.html .

M. Babadoost (217-333-1523; babadoos@uiuc.edu)

Vegetable Production and Pest Management

Herbicide Use Under Plastic Mulch
Many growers are using plastic mulch to improve earliness in vegetable production, but care must be given selecting and using a pre-emergent herbicide under the plastic mulch when not using fumigation. Thoroughly read the label to determine if an herbicide can be used under plastic mulch with your particular vegetable crop, and what restrictions may apply to your production method. Not all labeled herbicides for a particular crop can be applied under plastic, and some crops may have the restriction of row middle spraying only. In general, herbicides that are volatile in nature are restricted in their use under plastic. Injury has been shown to occur under plastic with volatile herbicides. For herbicides that do have a label for use under plastic mulch, there is usually a minimum 7 day wait period between application of the herbicide and plastic mulch to when planting can occur. Another restriction may develop depending on the application of the plastic mulch, particularly for producers who pull beds and lay plastic in one pass. Pre-emergent herbicides in general cannot be broadcast applied prior to pulling beds because the herbicide is mixed too deeply into the root zone, and may cause serious injury to the planted crop. An exception would be for producers who lay plastic flat without bed shaping--no further mixing of the herbicide deeper into the soil profile. Given the specific example of plasticulture tomatoes, Sandea (halosulfuron-methyl) may be applied as a pre-plant application under the plastic mulch for control of listed broadleaves and suppression of nutsedge. Sandea can be applied following the final bed shaping and just prior to the installation of the plastic mulch. The tomatoes may be transplanted into this treated area 7 days after the application and the installation of the plastic mulch. It would not be appropriate to broadcast-spray Sandea, then pull beds and lay plastic, without the possibility of injury to the transplanted tomato crop. The alternative is to spray row middles for control of weeds.

Elizabeth Wahle (618-692-9434; wahle@uiuc.edu)

An Information Network for Corn Earworm and European Corn Borer Trapping Data
I'm repeating this note from the previous issue ... please contact us if you're willing to share information from corn earworm traps or European corn borer traps.

Kelly Cook, a new addition to Crop Science's group of extension entomologists, will be establishing a data base for up-to-date information on counts of corn earworm and European corn borer moths from traps at various locations around Illinois. If you will be operating a corn earworm pheromone trap or a light trap or pheromone trap for European corn borer, we would like to enlist you as data provider. We used to collect information from corn earworm traps via post cards that trap operators would fill out each day and send to me (and to Roscoe Randell before me) every Friday. I sometimes summarized the previous week's data for the newsletter, but the information was already too old to be of much value by the time anyone could receive it. We can now use email and the web to make counts available immediately, so we would like to establish a network of data providers. If you're interested in taking part in such a project, please contact me at 217-333-6651 or weinzier@uiuc.edu or Kelly at 217-333-6651 or kcook8@uiuc.edu .

Rick Weinzierl (217-333-6651; weinzier@uiuc.edu)

This issue's Words of Wisdom" ... on farming ...

• A farmer is always raising things, but not as much as a middleman.
• In some places they raise more corn to feed more hogs to buy more land to raise more corn to feed more hogs.
• It isn't the farmer that lives on the fat of the land; it's the fat of the land that lives on the farmers.
• If you work hard and long enough on a farm, you can make a fortune - if you strike oil on it.
• Politics makes strange bedfellows - and strange authorities on the farm problem.
• A gentleman farmer is one who has the time to read all the government literature on farming. (Hmmm ... I wonder if that includes this newsletter. R.W.)

University of Illinois Extension Specialists in Fruit and Vegetable Production & Pest Management

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