/\42-l_ancaster Farming, Saturday, December 28, 2002 Grape Disease Control Update Wayne Wilcox Dept. Plant Pathology Cornell University New York State Agricultural Experiment Station, Geneva Time for the annual review of new cvelopments and various options on ..e disease-control front. As always. I’d ke to acknowledge the outstanding i am of grape pathologists here in Ge .,' va, including faculty colleagues (D. .adoury, R. Seem), research techni mns (Duane Riegel, Judy Barr), and laduate students and postdocs becom ig too numerous to mention, all of hose research efforts are the bases for lost of the following. Fungicide Changes And News 1. Benlate cancellation. As many now. Benlate is history. Worldwide lanufacture halted in 2001, sale and istnbution of product remaining m le “pipeline” will be allowed through te end of 2002. All registrations have <cen cancelled, although it still is legal use whatever product is on hand, i cording to label directions. EPA “ex cels” that use of such product will end i- 2003. and is seeking comment on its iroposal to revoke residue tolerances ihereby making any residue in fruit or 'i me illegal after a reasonable length of line). So, use what you have, but don’t ockpile. Benlate is a minor fungicide i >r N.Y. grape producers, used primar b to protect major pruning wounds >;ainst Eutypa. An application to reg ler a closely-related benzimidazole ungicides (Topsm-M) for use on i apes is currently being considered by ■ ‘ le EPA. 2. Phyt, Aliette, and phosphorous ProPhyt (potassium phosphite) is formulation of phosphorous acid "A) that is now labeled by the EPA to mtrol downy mildew on grapes (N.Y. gistration is still pending, but may be rthcommg by summer). It does not mtrol any other major grape disease, arious formulations of PA have been ed for approximately 15 years to con ol downy mildew in Australia, and 1 apeatedly have gotten excellent results dh several different formulations (m -uiding ProPhyt) in m\ own trials, en under very high pressure. PA provides good post-infection con ol of downy mildew, but because it is ghly mobile m the plant, the Aussies ■intend that it has only a few days’ nrth of residual (protective) activity fore it gets shipped down into the mis Thus, they tend to spray it after infection period has occurred, tank xing with a traditional protectant ich as manco/eb or copper) to pro le forward protection against the \t one In my own trials. I’ve applied at 14-day intervals without any sort tank mix and obtained virtually iipletc control every year, even in i ry wet seasons such as 2000, where » arly 70 percent of the berries on uns layed vines became diseased. How 's er, I haven’t scrutinized these trials > determine just when the various in cctton periods occurred with respect to he timing of applications. PA is so popular m Australia because t is quite cheap there (just a few dol ors per acre). Since ProPhyt is not yet sold in NY, I don’t know what the price will be locally (probably more ihan in Australia!). If they are priced light, this and other PA formulations that may come along could certainly find a place m eastern vineyards, par ticularly if an otherwise-desirable dis ease management program is weak on downy mildew control. They’re worth getting some experience with, provided they make economic sense. (A note on ates The ProPhyt label that I’ve seen pecifies a concentration of 0.3 percent, but this assumes a sufficient water vol ime for complete coverage. Thus, '.e’ve used 1 2 pints per acre prebloom +(assummg a spray volume of 50 gal/A bir complete coverages-) and 2.4 pints ,ier acre postbloom -(-(assuming 100 tal/A spray volumes-). Ahette is a product that has been ■round for many years, but just re ceived registration on grapes last sum ner. It breaks down into PA once prays have entered the plant, so ba ically does the same thing as PA pred icts but at a much higher cost (about AO-50 per acre at the recommended ite for grapes) Patent issues protected Miette against cheaper PA products in lie past, but the patent has now ev -11 ed Nationally, there are additional inducts containing PA that are being Id as nutritional supplements or Sant condilioneis." without claims their disease control activities ()l irse they’re etlcctiye nevertheless ic such product that we worked with t year is Prudent Plus, a mixture of is labeled for powdery mildew control as Nutrol), and various organic com pounds that are claimed to improve plant growth and health. In our trials last year, treated vines were virtually free of downy mildew and powdery mildew control was fair to good (better than Nutrol, worse than conventional fungicides). 3. Messenger. Messenger is a unique and interesting product now registered for control of grape diseases. It is a nontoxic protein that stimulates natu ral defense responses in some plants, thereby providing variable levels of re sistance to disease-causing organisms. The only problem is, there is no con vincing evidence that this occurs in grapevines. On the contrary, such an “induced resistance” response is notori ously difficult to elicit in grapes, al though many people (including a grad uate student in my own program) have tried to do so using various techniques and products. Furthermore, I have ob tained poor disease control in previous grape trials where Messenger has been used without additional fungicides, however, these were conducted a few years ago and it’s possible that the for mulation has improved by now. Results from several grower demonstrations that I helped evaluate last year in coop eration with a juice grape processor could best be described as “inconclu sive ” Although my experience with the product is limited, it is not consistent with some claims in recent advertising. Those interested in the product may wish to evaluate it for themselves on a limited, trial basis. 4. Serenade. Serenade is a product whose active ingredient is a soil bacteri um (Bacillus subtiilis), which is regis tered for biological control of powdery mildew and Botrytis In two trials last year (light disease pressure) we got good control of powdery mildew when Serenade was rotated with Sovran on both the hybrid variety Rosette and on Concord. In a Botrytis trial m 2000 (moderate pressure), four applications of Serenade alone (no other fungicide) provided zero control of that disease. We’re continuing to evaluate it this season. Limited experience causes me to still view it as an experimental prod uct: on a commercial crop, I’d be more comfortable experimenting to control powdery mildew rather than botrytis. A formulation being sold in N.Y is certi fied for organic production. 5. Other “alternative" products for powdery mildew. As discussed last year, a number of non-traditional prod ucts have been register ed recently to control pow dery mildew on grapes They work, to variable ex tents, but it helps to un derstand why. Powdery mil dew (PM) is an unusual disease, since the fungus that causes it lives almost entirely on the surface of infected leaves and berries (the powdery stuff you see when control breaks down). Thus, it is “naked” and subject to (temporary) eradication following top ical treatment with a range of products that don’t af fect other dis ease-causing fungi, which do their dirty work down inside the plant tissues where they’re protected from such treatments Some sueh products drt listed below • IN nl ro 1 (nionopotdssi uin pho s - ph.ite) We \e been working with this diKil purpose m<i leruil (lolioi nutrient plus powdery mildew fungi cide) every year since 1996, with mod erate results. In greenhouse tests, we’ve found that Nutrol provides no signifi cant control when applied before plants are inoculated with powdery mildew spores. In contrast, it provided signifi cant control when applied within 3-7 days after exposure to the spores, i.e., when applied directly to the developing PM colonies. This scenario suggests that Nutrol should be more effective when applied relatively frequently (repeated knock downs), rather than relying on residual protectant activity between sprays. In deed, we’ve gotten significantly better control in two seasons of fieid trials when applying 4 Ib/A every 7 days rather than 8 Ib./A every 14 days. I strongly suspect that this same general principle (one-shot knock-down against young colonies, with little subsequent protective activity) will apply to most of the ’’alternative” PM control prod ucts. Thus, they may need to be applied more frequently than many traditional products. • Kaligreen, Armicarb 100 (potassi um bicarbonate). We haven’t worked with Kaligreen, but Armicarb 100 has performed similarly to Nutrol in field trials. Photos in the trade press show ing dead PM fungus on treated plants also is consistent with the activity we’ve seen from Nutrol (topical, eradicative effects with no evidence of residual protectant activity). • Oxidate (hydrogen peroxide). Reg istered for control of powdery mildew and Botrytis. We haven’t worked with it. I believe the claims for PM control, but doubt those for Botrytis (see above). Will probably require frequent applica tions. Finally, remember that the activity of these topical materials is entirely de pendent upon their contact with the PM fungus. Don’t waste your time and money if you can’t provide thorough coverage. 6. Strobilurin fungicides These ma terials (Abound, Sovran, Flint) have been discussed at length for the last two years. Thus, just a few updates and re minders: • The “strobies” are retained pri marily in the waxy cuticle of treated leaves and berries. Thus, they are excel lent protectant fungicides when applied before an infection period begins but have only limited postinfection activity against most diseases (can’t get down into the deeper tissues where the fun gus gets established). Although they t 'J appear to have additional postinfection activity against powdery mildew (which lives mostly on the surface, re member), over-reliance upon such ac tivity increases the risk that the fungus will become resistant to these materials. • Resistance development is a very real and serious threat. Although no body understands why, it appears that the risk and speed of this happening may be significantly different for differ ent disease-causing fungi. For instance, several specific diseases on grasses and grains, cucumbers, and melons can no longer be controlled with strobies in some production regions, after only a few years of use. In contrast, similar problems have not yet surfaced with re spect to control of powdery mildew on grapes, despite considerable worldwide use, although there have been some overseas reports of problems with downy mildew. These products still work for us, but there’s no guarantee that will continue indefinitely. Because of their current importance to produc ers throughout the Northeast, they should be used conscientiously in order to reduce the probability of resistance developing, so that they will continue to be effective. • The only sure-fire way of reducing the risk of resistance is by reducing the number of sprays applied. Use the stro bies when they’re really needed, but don’t overdo it. The seasonal limit for wine grapes is four applications, but two or three is better. Juice grape grow ers may make up to three applications per season, but they should be sure to rotate with other fungicides to control the two mildews and black rot, even if they’re only applying two or three such sprays in total. And trying to “put out a fire” with these materials if disease gets out of hand is just asking for trou ble. This is a simple numbers game: the more fungal individuals that are pres ent, the greater the chance of selecting a resistant one when you spray. COMPLETE • In addition to the numbers game cited above, recent research suggests that resistance is more likely to de velop when strobies are applied to a growing fungus (i.e„ postinfection) rather than in a protectant mode which prevents spore germination and infection to begin with. Other than avoiding de liberate postinfec- tion applications, this means that ex cessive spray intervals (greater than 14 days) also should be avoided. For pow dery mildew, in particular, almost every day in the late spring and sum mer is a potential infection period (rain not necessary, temperatures very favor able). Thus, whenever a new (uns prayed) leaf emerges after a given fun gicide application, the next spray will be “reaching back” to provide postin fection control of whatever mildew may have started after that leaf emerged. Thus, the longer the spray interval, the more infections that may have occurred and the longer the necessary reach back activity will be. • Finally, consider these factors but keep them in perspective. The sky isn’t falling. These materials do work. But be responsible and keep it that way. 7. Mancozeb and mites. This has been talked about quite a bit the last few years. Trials supervised by Jan Nyrop and Greg English-Loeb in the Entomology Department have consis tently shown that fungicide programs that include regular mancozeb sprays will reduce the level of predatory mites (those that eat the spider mites), by an average of about 50 percent relative to programs where captan was substituted instead. In a few cases, this encouraged the buildup of spider mites, but not in the majority of trials. In an experiment last year, there was no effect on preda tors when mancozeb was limited to two sprays prior to bloom. These effects are real. As with so many things, the risk (incompletely de fined) and benefits (broad spectrum and economical disease control, 24 hr REI) need to be balanced. How to, spe cifically, is a personal decision. My feel ing is that mancozeb still has a place, but that it should not be used indis criminately. We’re still working on try ing to supply you more specific details than that. AUCTIONEERING SERVICE PUBLIC AUCTION Saturday, Jan. 4,2003 @ 9:ooam HUGE BUILDING SUPPLIES AUCTION DIRECTIONS: Fiona Harrisburg travel north on Rts 11&I5 to Liverpool Turn west onto Rt 17 and travel 3 miles to auction on right BUILDING SUPPLIES Lots & lots of vinyl windows in many sizes; boxes ol floor & wall vents, storm doors, screen doors. I piece fiberglass tub/showei units, toilets, medicine cabinets, molding, spindles, porch posts, 1/4” & 1/8” plywood back paneling, all A Grade, 5 styles to choose from, 4x4 plastic skids, 2’xs' metal workbenches w/pegboaid, lawn & garden tools, air compressor, ratchet straps. 21 yeat laminated shingles, framing lumber m 2\4x6 through 20‘ & 2x6xB through 20 ft. in good shape, 2x lx 10‘s, pressure treated lumber in 2xBx6, 2x12x6, 2x12x7 I\6 & lots ot other sizes available, linoleum, 14” & 24' conciete pipe 5/8” T&G OSB; Lots of Ixl2, Ix 6 & Ix 4 pine boards, large selection ol Ridge & Valley. nails & screws, skids of 1/2”, 3/4”, 1”, 1.5” thick 4’\B’ insulation; 1/2” toil back insulation R-3 6, 100's ot sheets ot 1/4”, 4’xB’ paneling, many fiberglass tub & shower units; handicap shower, prefinished drywall. steel entry doors, patio doors. 5/4" \ 6" wood/plastic decking boards, vanity tops & vanity bases, two sizes of air tire red wagons; circular saws, skids of 1/4”, 1/2”, 5/8”, 3/4” plywood & OSB; 2 wheel hand cart, parts cleaner, engine stand, levels, jack stands, floor jacks, tape measures, screw drivers, battery termi nals, elec tape, chains, rope, auto spotlight, utility knives, wrenches, wrecking bars, skids of Andersen screens & grills, mtsc vinyl siding & acc, & many more items too numerous to mention LOGS & LOG SIDING Skids of 2xB log siding, 4x6 D logs, 2x6 log siding, 2x6 & 2x12 white pine boards VEHICLES 1840 Cub Cadet riding mower. 50" deck, full hydrostatic w/l month old 20 hp Vanguard V-Twm motor, 50' pup trailer, road worthy, 45', 13’6" van tiailer. road worthy & water tight. 33' Nitty Ldt, selt contained Pickup loads ot Flea Maiket items welcome the day of the auction Call TB tor moie info TB is open for regular business Mon, Tues, Thurs, & Fri. 8:00 to 5:00, Wed. & Sat. 8:00 to 12:00 Auction Note; Call 717-444-7230 for auction informa tion 2003 Auctions 2/1, 3/1. 4/5, 5/3. 6/7, 7/26, 9/6, 10/4, 11/1. 12/13 all stall at 9 00am Owner: TB Lumber, 717-444-7230, RR I Liverpool PA - AY-00022 3L TERMS: Cash or good PA Check oi ciedit card with 2 3 r { accounting tee Matcnal must be lemoved liom site h\ 1/0/03 Not lesponsihle (oi lost oi stolen items Olhci teims given Ihe da\ ol auction \ll items suh|ecl to pnoi sale OPEN 6 DAYS A WEEK KENNETH E MASSINGER NEIL A COURTNEY RR 02. Box 985 R D #1 Box 239 McClure, PA 17841 unit Richfield, PA 17086 (570) 658-3536 43M (570)539-8791 AU-001532-L AU-002651-L
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