Management and control of apple powdery mildew

Transcription

1 Management and control of apple powdery mildew Angela Berrie, Robert Saville Xiangming Xu East Malling Research

2 Apple powdery mildew The disease Second most important disease of apple in UK Mildew is a debilitating disease affecting most tree parts and reducing yield and fruit quality Reduces yield directly by reducing number of viable blossoms and indirectly by reducing tree vigour High incidence of mildew results in russeted fruit Many UK commercial apple orchards have high incidence primary and secondary mildew

3 Apple powdery mildew Why is it difficult to control? Primary mildew on flowers and shoots provides instant inoculum Young leaves are most susceptible Mildew conidia do not need surface moisture to germinate on leaves So, provided there is young leaf tissue (growing shoots) and it is not raining every day in summer is an infection day for mildew In favourable weather (warm - > 18 o C, cloudy, humid) the fungus can infect leaves and produce sporing mildew colonies in about 4-5 days So mildew can build up rapidly in summer on extension growth Fungicide protection required as long as shoots continue to grow Need sprays per season on a susceptible cultivar If primary mildew is low than fungicide inputs can be managed by adjusting product choice, dose and spray interval to match the mildew epidemic

4 Active ingredient Fungicides for apple powdery mildew in UK Fungicide product eg Mode of action Max No of treatments Chemical group cyflufenamid Cosine E/P 2 amidoximes fenbuconazole Indar E/P 10 DMI (triazole) bupirimate Nimrod E/P 4 Hydroxypirimidine kresoximmethyl Stroby P 4 Strobilurin (Qol) meptyldinocap Kindred P 2 Phenyl-acetamide myclobutanil Systhane E/P 10 DMI (triazole) penconazole Topas E/P 10 (3) DMI (triazole) Potassium bicarb pyraclostrobin + boscalid pyraclostrobin + dithianon various E Max dose 60kg/annum inorganic Bellis P 4 Strobilurin (Qol) + SDHI Maccani P 4 Strobilurin (Qol) + quinone Sulphur various E/P See label inorganic

5 Apple powdery mildew Many orchards mildew is difficult to control Several possible reasons but a main contributory factor is limited range of fungicides available Heavy reliance on triazole fungicides myclobutanil and penconazole HDC-funded project to study reduced sensitivity of mildew to fungicides LINK project SCEPTRE - Main objective to identify new fungicides and biofungicides for mildew control

6 Monitoring mildew sensitivity to fungicides (triazole, strobilurin, SDHI) Potted rootstocks (MM106) or seedlings (Malus bittenfelder) raised in mildew-free glasshouse Treated with range of 4 levels of fungicide concentrations of Systhane (triazole), pyraclostrobin (strobilurin), fluopyram (SDHI) On day of treatment 1 st fully unfurled leaf on each shoot labelled on each plant, up to 5 shoots selected on rootstock, 1 shoot on seedling. 4-5 per fungicide per concentration Treated plants then placed in orchards around Kent where mildew control known to be a problem Left in orchards for hours. Then moved back to contained glasshouse compartment Number of powdery mildew lesions recorded on tagged leaf and 3 leaves below this

7 HDC funded project Monitoring mildew sensitivity to fungicides

8 Monitoring mildew sensitivity to fungicides - Results Apple seedlings % of the control Luna lesion Site A Site B Site C Luna incidence SDHI 0 C1 C2 C3 C4 0 C1 C2 C3 C % of the control Systhane lesion Systhane incidence triazole 0 C1 C2 C3 C4 0 C1 C2 C3 C % of the control Vivid lesion % of the control Vivid incidence strobilurin 0 C1 C2 C3 C4 0 C1 C2 C3 C4

9 Monitoring mildew sensitivity to fungicides - Conclusions Established mildew response to a range of concentrations of 3 fungicides in several orchards in Kent Despite the presence of high mildew incidence, and favourable weather not all the exposed rootstocks / seedlings developed mildew following exposure so limited data set Differences in the dose-response of mildew among sites tested were greatest for Systhane (myclobutanil) Largest within-site variability in the dose-response of mildew at a given site was also greatest for myclobutanil (triazole) Data limited but suggest existence of reduced sensitivities to myclobutanil and to much lesser extent for pyraclostrobin (QoI) and fluopyram (SDHI)

10 Apple powdery mildew Control % mildewed leaves on apple shoots cv. Cox assessed at various times following treatment with effective or partially effective fungicide 100 % mildewed leaves Untreated Partially effective fungicide Effective fungicide 0 08/06/ /06/ /06/ /06/ /07/ /07/ /07/ /07/ /08/ /08/ /08/ /08/ /08/ /09/2011 Date assessed

11 Control of apple powdery mildew Fungicide and biofungicide evaluation Test products Fungicides Biofungicides and alternative products Trial year Small plot orchard trial testing single products Small plot orchard trial testing single products Pot trial using MM106 rootstocks testing single products Small plot orchard trial using fungicide programmes Pot trial testing single products and some programmes Large plot orchard trial testing whole season programmes Small plot orchard trial testing biofungicides in programmes with fungicides

12 Fungicide evaluation - Method Small plot experiment on cv. Cox 3 tree plots 4 reps Treatments applied using Stihl air-assisted sprayer at 500 L/ha Routine fungicide programme for scab and mildew control from bud burst to start of trial 5 spray rounds applied at approx day intervals from mid June Trial targeted at control of secondary mildew Mildew assessed on top 5 leaves on 7 occasions

13 Fungicide evaluation - Treatments 2012 Treatment Active Sceptre code Chemical group number ingredient 1 Untreated Systhane myclobutanil DMI 3 APL-32 SDHI + DMI 4 APL-128 QoI + phthalimide 5 APL-17 SDHI + DMI 6 APL-25a SDHI + DMI 7 APL-87 8 APL Cosine cyflufenamid 10 APL-158 potassium bicarbonate + sulphur Aryl-phenylketone SDHI +arylphenyl-ketone Phenyl acetamide Inorganic

14 Fungicide evaluation - Results 2012 % Mildewed leaves 2012 % mildewed leaves Untreated Systhane APL-32 APL-128 APL-17 APL-25a APL-87 APL-159 APL-89 APL /06/ /06/ /06/ /07/ /07/ /07/ /07/ /08/ /08/ /08/2012 Date assessed 22/08/ /08/ /09/ /09/ /09/2012

15 Fungicide programme evaluation 2013 Treatment 1 13 June 2 20 June Product / Timing 3 3 July 4 17 July 5 26 July Untreated Standard Systhane Systhane Systhane Systhane Systhane P1 APL-32 APL-32 Cosine APL-87 APL-32 P2 APL-17 APL-17 Cosine APL-87 APL-17 P3 APL-25a APL-25a Cosine APL-87 APL-25a P4 APL-128 APL-128 Cosine APL-87 APL-128 P5 APL-32 APL-32 APL-159 APL-159 APL-32 P6 APL-32 APL-32 Kumulus DF Kumulus DF APL-32 Experimental 1 Talius Talius Talius Talius Talius Experimental 2 APL-118 APL-118 APL-118 APL-118 APL-118

16 Fungicide programme evaluation - Results 2013 % mildewed leaves on apple shoots cv. Cox assessed at various times following treatment with fungicides programmes in % mildewed leaves Untreated Systhane P1 P2 P3 P4 P5 0 14/06/ /06/ /06/ /07/ /07/ /07/ /07/ /08/2013 P6 Talius Exp 2 Date assessed

17 Fungicide programme evaluation - Results 2013 Untreated Systhane Programme 5

18 Programme evaluation Conclusions Mildew in untreated plots increased rapidly to almost 100% All treatments reduced the incidence of mildewed leaves Least effective was the standard treatment Systhane Most effective treatments were P1, P5, Talius (proquinazid) and Experimental 2 In 2014 full seasons programmes (10-15 rounds) of products were evaluated in 2 experimental programmes compared to a standard programme At the end of the season mildew control was better in the 2 experimental programmes

19 Control of apple powdery mildew Biofungicides evaluation 2012 Pot experiment using MM106 rootstocks 7 pots per plot, 6 replicates per treatment Mildew-infected potted trees present in each block as mildew inoculum source Treatments applied using knapsack sprayer at 1000 L/ha 5 spray rounds applied at approx. 7 day intervals from mid-june Mildew assessed on 3 occasions on top 5 leaves

20 Biofungicide evaluation Products Treatment number Sceptre code Active ingredient Product type 1 Untreated Untreated - 2 Systhane myclobutanil fungicide 3 APL-105 Plant extract 4 Potassium bicarbonate potassium bicarbonate Inorganic salt 5 Kumulus DF Sulphur Inorganic fungicide 6 Kumulus DF + Potassium bicarbonate potassium bicarbonate + Sulphur Salt + fungicide 7 APL-06 bacteria 8 APL-38 bacteria 9 APL-157 Hyper-parasite 10 APL-90 Plant extract 11 APL-115 Alternative chemical

21 Biofungicide evaluation

22 Biofungicide evaluation Results % mildewed leaves mean of 3 assessments Untreated APL-06 APL-115 APL-38 APL-105 APL-157 APL-90 potassium bicarbonate Kumulus + pot bicarb Kumulus Systhane

23 Biofungicide evaluation Conclusions Mildew incidence in untreated trees >70% mildewed leaves All of the test products reduced mildew incidence but only about 30% compared to untreated Best control achieved with Systhane and Kumulus Kumulus performed better on own than in combination with potassium bicarbonate

24 Evaluation of biofungicides / fungicide programmes 2014 Evaluation of programmes combining fungicides and biofungicides Small plot orchard trial (3 tree plots) on apple cv. Cox 4 replicates Sprays applied at 500 L/ha. 10 spray rounds at ~7 day intervals Systhane as fungicide standard 8 Fungicide / biofungicide programmes evaluated 2 managed programmes where product choice determined by disease incidence Mildew assessed on top 5 leaves on 8 occasions

25 Evaluation of biofungicide / fungicide programmes 2014 Treatment Number 1 22 May 2 2 June 3 9 June 4 16 June 5 23 June Product / Timing 6 30 June 7 7 July 8 14 July 9 21 July July Systhane Systhane Systhane Systhane Systhane Systhane Systhane Systhane Systhane Systhane 3 APL-32 APL-32 APL-105 APL-105 APL-105 APL-105 APL-105 APL-105 APL-105 APL-32 4 APL-32 APL-32 APL- 157* APL- 157* APL- 157* APL- 157* APL- 157* APL- 157* APL-157* APL-32 5 APL-32 APL-32 APL-90 APL-90 APL-90 APL-90 APL-90 APL-90 APL-90 APL-32 6 APL-32 APL-32 APL-06 APL-06 APL-06 APL-06 APL-06 APL-06 APL-06 APL-32 7 APL-17 APL-17 APL-105 APL-105 APL-105 APL-105 APL-105 APL-105 APL-105 APL-17 8 APL-17 APL-17 APL- 157* APL- 157* APL- 157* APL- 157* APL- 157* APL- 157* APL-157* APL-17 9 APL-17 APL-17 APL-90 APL-90 APL-90 APL-90 APL-90 APL-90 APL-90 APL APL-17 APL-17 APL-06 APL-06 APL-06 APL-06 APL-06 APL-06 APL-06 APL managed 12 managed APL-17 APL-17 Talius Talius APL-06 Cosine APL-157 APL-06 APL-146 APL-17 APL-32 APL-32 Talius APL-06 APL-157 Cosine APL-06 APL-157 APL-146 APL-32 Fungicide Biofungicide

26 Evaluation of biofungicide / fungicide programmes 2014 Results

27 Evaluation of biofungicides / fungicide programmes Conclusions High incidence of primary mildew in the orchard at the start of the trial Untreated plots mildew rapidly increased to 100 % mildewed leaves All programmes reduced disease relative to untreated An initial decrease in disease observed at the start of ALL the programmes (coinciding with chemical fungicides) Mildew epidemic increased once biofungicides were included in the programme. Managed programmes were as good/better than Systhane standard.

28 Control of apple powdery mildew Overall conclusions Promising new fungicide products for mildew control were identified When these products are registered they will most likely be limited to a maximum of 2-4 sprays per season This presents problems for a disease which requires sprays per season for control Biofungicides were only partially effective and in general (especially microbial-based products) tend to be expensive In orchards of less susceptible cultivars where mildew incidence low biofungicides could be used as part of a managed programme

29 Control of apple powdery mildew Future research HDC-funded Future work will focus on evaluating plant strengtheners / elicitors These may be cheaper and if effective could form the basis of a programme with reduced fungicide use They may also be effective against other apple diseases and possibly have benefits for fruit yield and quality

30 Acknowledgements Thanks to HDC and Defra for funding and to Trials team at EMR for applying the sprays Karen Lower, Tom Passey, Joyce Robinson for assistance with the trials

31 SCEPTRE - Consortium members