Disease Management Recommendations for rainy/wet conditions
- provided by Dr. Annamiek Schilder, Michigan State University plant pathologistThe challenges of disease control during rainy spells
Protect new grape shoots from early-season fungal diseases
by Rufus Isaacs, Michigan State University Extension, Department of Entomology
Time spent monitoring vineyards for cutworms and flea beetles can avoid costly pest damage. There are good rules of thumb for deciding whether damage from these insects warrants control, and information on scouting and other management components fromMichigan State University Extension is provided
Top 10 Insect Pests
The top ten insects that have been identified for Nebraska are insects that have recently been found in Nebraska vineyards either in large quantities or causing great amounts of damage. This list may vary greatly by area and grape cultivar, but can be used as a general guideline of what insects may be found in Nebraska vineyards.
Grape Cane Borer (Alias: Apple Twig Borer)
By Paul E. Read, Professor
University of Nebraska Viticulture Program
Recently, several growers have reported infestations of the grape cane borer, originally named the apple twig borer (Amphicerus bicaudatus). With the assistance of UNL Department of Entomology scientists Fred Baxendale and Jim Kalisch, it has been identified and the following recent article written by Cornell University (New York) scientists has been found. Information about this insect is sparse, but the following approaches are suggested.
- Remove and destroy all infested and damaged canes and other plant parts. Incineration, where legal, finely chopping or burial are recommended.
- As noted in the following article (Dr. Baxendale concurs with this suggestion), control of adults by spraying with Imidan in early to mid-May is suggested, with a follow-up spray in late May or early June to kill recently hatched larvae.
- Treat and/or remove other host species near the vineyard (apples, scrub trees, etc.). This insect is not easy to control because once it is inside the canes, no kill can be effected by insecticidal sprays. If you have experienced problems with this insect, please let me know. Dr. Baxendale and I will be trying to learn more about this insect's abundance, relative severity, and distribution, with the ultimate goal of reducing or eliminating damage caused by this pest.
Grape Cane Borer Biology and Controlby Timothy E. Martinson and Greg English-Loeb
Grape Cane Borer, Amphicerus bicaudatus, has once again been a topic of discussion among growers in the Finger Lakes. The consensus among growers I have spoken with is that problems seem to be increasing in area vineyards, not just in the Keuka area but also in some locations on Seneca Lake.
For those of you who are unacquainted with the cane borer, the damage comes from adults that bore into live canes -generally but not always in nodes near the base of the cane. Although these holes are about 3/16" in diameter, they are hard to see without searching closely. Retained canes often die past the entrance hole, and canes with borer in them often break during the typing operation. In a cane pruned vineyard with '4 cane' vines, loss of one cane would amount to 25 percent of the potential crop. In cordon/spur trimmed vineyards, damage would be somewhat less, but may make it more difficult to maintain permanent cordons.
What we know about cane borer comes from a study done by Dr. George Shaefers and Zeke Mendel, of Taylor Wine Company, between 1981 and 1983. In a literature search, we found on a couple of papers on this pest, along with a reference to an unpublished thesis from
Texas. Dr. Shaefer's study looked at economic impact in an' Aurore' vineyard, and included a very preliminary laboratory insecticide trial.
Adults are brown to black in color, shaped like a cylinder, and 3/8" long. Cane borer overwinters in the adult stage, within burrows made in live canes. As weather warms, they become active in late April and early May, and tend to fly around in evening hours near dusk (the report mentions 8:30 PM). At this time, they are thought to make few new entries, with most limited to dry wood. Presumably adults mate around this time of the year. Egg laying starts in mid May, and peaks in mid-June. Eggs are reportedly laid singly under loose bark -either on live vines or pruned wood on the vineyard floor. Eggs hatch around mid-June, and larvae burrow "directly into the dead or dying canes." Early feeding is just below the bark, while older larvae enter the pitch (spongy area in the middle of the cane), leaving a sawdust-filled channel behind. Larvae complete their development and form pupae in mid-August, and adults emerge in mid-September. As canes harden off and form periderm, the adults enter one-year-old wood and the current year's canes, and again feed in channels in the middle of the canes. This is when the economically significant damage to healthy wood occurs.
Shaefers reported that in one heavily infested Aurora vineyard, 30 percent of the dead canes showed evidence of cane borer feeding, while a less-heavily infested area within the same vineyard had about 19 percent of the dead canes attacked. He also reported that "Counts revealed that one out of nine vines had a dead cane, and one out of 47 vines had one cane attacked by borer." What I interpret this to mean is that although 1/3 of the 'dead canes' may have died due to borer feeding, only 10 percent of the vines had a dead cane, and only two percent of vines had one cane borer in them. If these figures were accurate for a calle-prulled vineyard with four canes per vine (the training system was not mentioned), the potential crop loss would have been one of 188 = 0.5 percent crop loss.
Shaefers tested eight insecticides in the laboratory, several ofwhich are no longer available. The exact testing method was not indicated, and each material was tested on only 10 adults. Of currently available insecticides, Imidall treatment after 48 hours resulted in 10 dead adults (100 percent of those tested), while Sevill (carbaryl) results in five dead (50 percent) mortality. It's important to keep in mind that these were laboratory tests, and the results may not translate into effective control at the field level.
Controlling Cane Borer
To my knowledge, no rigorous insecticide trials for cane borer have been done. There are reasons for this -the main one being that the life cycle of this pest does not lend itself to conventional small plot trials. The insect is protected for most of the year within the vine (and not likely to contact insecticide), and the only way to evaluate efficacy (e.g. ofa spring application) would be to look for adults the following winter. Presumably, they move around a bit, and they have several woody plant hosts (all common in the area), so it's hard to predict how large an area you would have to treat to see any effect. Given the lack of research, the best guidelines we can offer at this time are based on educated guesses of what might be important:
- Remove or Chop Brush. Dead canes and wood remaining on the vineyard floor may serve as a reservoir for adults, and also may harbor larvae throughout the season. Thoroughly chop brush, or remove and destroy as much as possible before adults become active in the spring. Consistent with this recommendation is the result of a study conducted in Italy where they found that by burning pruning material before the next field season helped eliminate a cane borer problem. Note that hedged pruned vineyards, with an abundance of old, dead wood, may provide good places for larvae to develop.
- Timing Sprays. If you decide to try an insecticide, it makes sense to target active adults before they lay eggs. Recall that adults are active from mid to late May, and are most active in the evenings. Another potential target would be the larvae after eggs hatch but before they burrow into the wood. Again, Shaefers' study indicated that that the peak timing for eggs would be from early to mid June. It's possible that with thorough coverage, a spray at this time might significantly reduce the number of larvae that develop. Again, this is all guesswork.
- Insecticides. The only insecticide currently registered for cane borer in New York is Imidan 70 W, although we have conducted no trials to test its efficacy -and thus no reason to recommend it over other materials. It's possible that broad spectrum insecticides applied for other labeled pests might also provide some control of cane borer, if applied at the appropriate time. Narrow-spectrum materials such as miticides, BT (Dipel, biobit) and Provado (imidacloprid) will not provide control. As this pest has not been exposed to many insecticides, we presume that resistance is not a problem.
- Evaluate Objectively. Be careful in assessing the extent of the problem. It's easy to overestimate how many cane borers are out there and how much damage they are doing. It's dismaying to have a cane snap off during tying because of cane borer injury. But it makes a difference whether or not damage is present on one cane in 100 or five in 100. Remember that it's the infestation in the canes you leave, not in the canes you trim off, that will affect yield. Think of the numbers you find in relation to the size of your vineyard, and don't overreact. In the few vineyards I have surveyed, I've generally been surprised at how few I find, although I recognize that each individual can destroy a carefully selected cane or cut short the useful life of a cordon arm.
I understand that the information we have for this pest is incomplete, particularly where effective control measures are concerned. Greg English-Loeb is making some information observations of cane borer behavior at his lab in Geneva. I also think it would be useful to attempt to test a few of the registered insecticides at an appropriate site, even if there's a chance that a formal trial won't work. I'll be looking for cooperators to set up an informal trial this spring. If you think you have a block with enough cane borer damage to attempt a trial, please give me a call at (315) 536-5134, or e-mail at tem2@ cornelledu.
Source: Finger Lakes Vineyard Notes, April 2, 2002.
By Paul E. Read, Professor, University of Nebraska Viticulture Program
Grasshoppers seem to be a problem in the making. Dr. Fred Baxendale, Extension Entomologist suggests the following Neb-Fact articles:
A Guide to Grasshopper Control in Yards and Gardens
Nebraska Cooperative Extension NebGuide G1633
A Guide to Grasshopper Control in Cropland
Nebraska Cooperative Extension NebGuide G1627
A Guide to Grasshopper Control on Rangeland (revised June 2002)
Nebraska Cooperative Extension NebGuide G1630
While the grasshoppers are small it is important to treat the perimeter area around your vineyard and also the cover crop between the rows. If not treated while small, the grasshoppers will become larger and more voracious. If the weather remains dry they may begin eating the grapevines and grape berries for moisture.
For further advice contact your County Extension Educator
Sustainable Pest, Disease and Weed Management - Andy Allen & Donn T Johnson
Eliminating Herbicides in the Vineyard - Ben Loseke
Disease Identification on Nebraska's Major Cultivars
Mulches & Groundcovers for Sustainable Vineyard Floor Management
A Pocket Guide for Grape IPM Scouting in the North Central and Eastern U.S. 2004.
Rufus Isaacs, Annemiek Schilder, Tom Zabadal, and Tim Weigle. Michigan State University Extension Bulletin E-2889. 112 pp.
Grape Pest Management. 1992. D.L. Flaherty et al. University of California, Publication 3343. 400 pp.
2004 Midwest Commercial Small Fruit and Grape Spray Guide. 2004. Paul Read,
Fred Baxendale, John Watkins, and Alex Martin. University of Nebraska Extension Service. 68 pp.