(Uncinula necator Schweinitz Burrill)

Transcription

1 Sustainable control of grapevine powdery mildew (Uncinula necator Schweinitz Burrill) in vineyards in South Australia Peter Crisp B Ag Sc (Hons), The University of Adelaide Thesis submitted for the degree of Doctor of Philosophy in The University of Adelaide February 2004 Plant and Pest Science School of Agriculture and Wine Faculty of Sciences

2 2 ", ", " " " ",,,,,,» ",1 1 Introduction, 1 12 Organic agriculture " ' HH,' H'H' 2 13 Powdery mildew (UI1ciI1111a necator), 4 L3,I History of the disease, 4 13,2 Disease cycle and epidcrruology, ',5 1 A ofpowdery mildew, L4J Cultural cor,trols H' IA,11 Canopy strcture,, " " H,HH I A 12 Other cultural control methods H', 8 lad "'atul enemies, ", <" " " " H ' 142 Resistance 9 1,43 Chemical control" 1431 Current control methods L4,3,2 Spray timing 14 I AA Biological controls, 1 A41 AmpeloTnJ'ces quisquajis " 1 AA2 Badllus subtilis," L4A3 Pseudomonas spp, L4AA Trichoderma spp, H ",,' <' L4A5 Other microbial agents, L4A6 Mites """" H L4,5 Novel fungicides < L45J Inorganic salts las,2 Surfactants" I A53 Milklwhcy, 1,4,5A Compost extracts" ' L4 5,6 Chitosan/chitir, " " <,29 I A5,7 'vr formulation L5 Oils " " " " «,,, " H 30 L5, Canola oil«,,,32 L52 Neem oil", 33 L5,3 Eucalyptus oil 34 L5A Tea tree oil, 1, 5 5 Other lblia coatings",,, 34,6 Summary,,8,8 «,8 15, 17, "",, ,9, 12, 12,20 <,21,H,<, 22 23,,25,,25, ",27 27,,28 ",37 " " " ' 00'" 2l Greenhouse experiments 211 1Vlaintenance of vines 212 jtloculation, t::eatment and assessmeyl; ofvlt!t:s 38 2,1 Management 22 Field expz;xirnents ",A2 22, Field sites A2 LL 11 Temple Bruer WlDes vineyards 2,2,I2GJenara Wines vineyard" 2,213 Mountadam VmeyanL 2,2, j A Wanipadnga vltieyl\rcl 2,23 Methods for field exllr,cmc'nts 2,2,4 Mal13g"mcnt 50 H'HHH,H," 'HHH«"'««,«",,«52 3 Inrroduction 52 3,2 Materials and methods, 54 3,2,1 Lxperimcnt ,,, 54,, 37 46

3 3I2 E)'erimem Results 331 Experiment Mcthmls and flalcrials 421 T",n, t" 422 Gle,saru 432 Glcnara Willes Vllli:ard 3; ev nennn:>-ttt 2000/ ' / , MOll!ttadarn 42,4 \Varriparinga, " _ 43 Resul!s 431 Wine, VlW'Varu Mountadam Discussion 'H,,,,78 ", 81 " KeSUltB methods,,,,, ",, " 521 De!ec!ion free 522 eiec!njn m}()rmlco]1y Electron spin spec!rometry Scanning elec!ton microscopy Dis{;usston Introduction 6,2 and materlals 62 [f200l 622 2I2()Ol 62,} E,,)erimc11l (,2 A EX1}rimcn! [ U i Reau itl 631 [,,,oer11110nl 632 ExneTiIl1cni 633 EX1enmCni 3/200 I 634 1/2UOL llx 72,1 "'ines P' 722 Wan:itlsrin 'a 7 22 i WanifJaringa eyr,erime'g' I, " 12! 124 CiA DiscirssiOlL, ,1 D,aclissioli 2001" "" Mattlrials and methods 72,2, Gl(:mr WineS l/2002",,,, i 132, " ,,, , i37,," 13 " 139

4 VIl il , Resuhs 831 Temple Bruer Wmes vrneyard "",prim"n! 832Yield and quality assessment 833 Temple Bmer Wones vineyard experiment 2_ 8A DiscussIon ",,",, 9, ",, " - Ul, r:ji'l APF'ENlJIX J - J 74 Map 1 Glenara Wines and MOllutadam 174 Map 2 Warriparinga 175 "'ap 3 Temple Emee Wines \'irlevar GE1,EFtAL A 2,1 Yeast extract medium for Bacillus lw71111s A A 23 'vr Formulation A 24 Wheast 3-,, 179,,, , IM 1 44, ,

5 Abstract Grapevine powdery mildew, caused by the fungus Uncinula necator Schweinitz Burrill, is a major disease affecting grape yield and quality worldwide In conventional vineyards, the disease is controlled mainly by regular applications of sulphur and synthetic fungicides, such as demethylation inhibiting fungicides (DMls), and in organic agrculture by sulphur and canola-based oils The impending restrictions on the use of sulphur in organic viticulture, the development of resistance to DMls in Australia and elsewhere, and the demand for residue-free grapes create a need for effective alternatives to sulphur and synthetic chemicals This research has identified potential replacements for synthetic fungicides and sulphur in the control of powdery mildew, such as milk, whey, bicarbonates and canola oil-based sprays A series of greenhouse experiments was conducted to evaluate 34 potential novel materials and biological agents for efficacy in controlling powdery mildew The most effective treatments applied were Bacillus subtilis (which reduced disease by 94% compared to the untreated control), Synertrol Horti-Oil (a canola oil-based product, 92%), milk (70%), whey (64%) and Ecocarb (potassium bicarbonate, 58%) Milk and whey provided increased control of powdery mildew as the concentration increased The efficacy of milk tended to decrease as the fat content of the milk was reduced The materials that were most promising in the greenhouse were then assessed in field trials in commercial vineyards Applications of milk, whey and mixtures of a canola oil-based product and potassium bicarbonate, applied at rates of 300 Uha to 1000 Uha depending on canopy development, reduced the severity of powdery mildew The severity of powdery mildew on vines sprayed with a 1:10 dilution of

6 milk, 45 gil whey powder and mixed programs was not significantly different from that on vines sprayed with sulphur (wettable powder, 3 gil) However, the relative control of powdery mildew by the test materials in field trials was highly dependent on the degree of coverage of the plant surface achieved In vineyards where coverage was compromised, the degree of control of powdery mildew was reduced, often to commercially unacceptable levels Electron spin resonance (ESR) and scanning electron microscopy (SEM) were used to investigate the possible mode or modes of action of milk and whey in the control of powdery mildew The ESR experiments showed that production of oxygen radicals by various components of milk in natural light was associated with reduced severity of powdery mildew SEM images showed that milk and whey caused the hyphae d U necator to collapse and damaged conidia within 24 h of treatment Hydrogen peroxide, applied as a source of free radicals, also caused collapse of the hyphae of U necator within 24 h but did not damage conidia, and appeared to stimulate germination Lactoferrin (an antimicrobial component of milk) ruptured conidia, but damage to hyphae was not evident 1:1 iactoferrin-tteated samples until 48 h after treatment The results suggested that fats, free radical production along with the action of lactoferrin, and possibly other proteins, are associated with the control of powdery mildew by milk Novel soft fungicides, such as milk and oil plus bicarbonate mixtures, were effective alternatives to sulphur and synthetic fungicides in certain South Australian conditions Biological agents (including B subtilis, which was highly effective in greenhouse experiments) did not provide acceptable control of powdery mildew in the vineyard