Postharvest diseases of avocadosfrom orchard to market Cultural and Chemical control

Transcription

1 2/12/14 Postharvest diseases of avocadosfrom orchard to market Cultural and Chemical control Dr Kerry Everett Mt Albert Research Centre Auckland, New Zealand 1

2 2/12/14 Climate Comparison Uruapan Mexico and Tauranga New Zealand Data redrawn from Climate Comparison La Serena Chile and Tauranga New Zealand Irazabal, F.G. 1. History and Development of the Avocado in Chile. California Avocado Society Yearbook 85: Data redrawn from 2

3 2/12/14 Climate Comparison Lima Peru and Tauranga New Zealand Data redrawn from Mexico California Australia Chile New Zealand Peru South Africa J F M A M J J A S O N D Irazabal, F.G. 1. History and Development of the Avocado in Chile. California Avocado Society Yearbook 85:

4 2/12/14 Comparison of exports by value (USD) 12 data New Zealand avocado exports Source: NZ Avocado Growers Association Inc. & Avocado Industry Council Ltd. Annual Report 14 4

5 2/12/14 Two postharvest diseases Body rots (antracnosis) Stem-end rots (pudrición peduncular) 5

6 Mean no. isolations/ fruit 2/12/14 What causes rots? body rots stem-end rots C.a. C.g. B.p. B.d. P. Fungus Colletotrichum acutatum Colletotrichum gloeosporioides Botryosphaeria parva Botryosphaeria dothidea Phomopsis sp. 6

7 2/12/14 Are rots a problem? USA Three strikes and you are out (late 9 s) Rots Measles = rots in green fruit Australia 5% of consumers do not repeat purchase because of poor quality due to rots (199 s) * Large backlog of NZ fruit in the market place leading to extended storage and fruit age problems (1997) Three issues rots fruit age measles * Ledger, S., Campbell, T., Banks, A., Atkinson,I, Kernot, I. and Fullelove, G Internal quality of avocados in retail shops. Queensland Department of Primary Industries Internal Report (Avoman). 23pp. What did we do to fix it? Research Avocado Rot Survey Three year survey of orchards to identify cultural and grower practices that affected rots Followed it up with replicated trials Determined: the storage limits of fruit the criteria for infection the relationship between lenticel damage and measles Logistics Reviewed the research that had already been conducted in NZ Tightened up timeframes in the logistics pathway Cooperation amongst exporters to rationalise flow of avocados to the market 7

8 Mean no. of fruit with stem-end rots (%) Mean no. of fruit with body rots (%) 2/12/14 Avocado Rot Survey Sampled 8 orchards in January each year for 3 years Sampled an additional 13 orchards for 2 of the 3 years Assessed fruit from each orchard for rots Collected orchard parameters including spray diaries and weather Analysed the data Everett KR, Boyd LM, Pak HA, Cutting JGM 7. Calcium, fungicide sprays and canopy density influence postharvest rots of avocado. Australasian Plant Pathology 36(1): Fungicide sprays reduce rots R 2 =83% P=.2 Y = X 3 25 R 2 =74% P=.4 Y = X -.4 X Mean no. of fungicide applications Mean no. of fungicide applications 8

9 Body rots (mean severity) no. of fruit with body rots (%) 2/12/14 Nutrition affects body rots Ca+Mg K Y= exp(-x/.2) -.51 R 2 = 56% Rainfall inversely related to body rots P=.3 R 2 =57.4% Y=.25-.2X mm rainfall days before picking 9

10 Log (no. of fruit with body rots ) Log (no. of fruit with body rots ) Ca+Mg K Ca+Mg K Rainfall (mm) Rainfall (mm) 2/12/14 Rainfall inversely related to body rots Temperature ( C) 4 days BH Rainfall (mm) 3 days BH Ca+Mg K 1.8 P=.1 R 2 =75.6% 1.6 Y= X P=.3 R 2 =63.3% Y= X P=.2 R 2 =7.4% Y= X P=.24 R 2 =67.2% Y= X P=.3 R 2 =66.2% Y=.4+.2X Rainfall inversely related to body rots Temperature ( C) 4 days BH Rainfall (mm) 3 days BH Ca+Mg K 1.8 P=.1 R 2 =75.6% 1.6 Y= X P=.3 R 2 =63.3% Y= X P=.2 R 2 =7.4% Y= X P=.24 R 2 =67.2% Y= X P=.3 R 2 =66.2% Y=.4+.2X

11 body.rots mean severity (body rots) 2/12/14 Canopy index influences body rots dead branches + (canopy density x leaf height inside canopy)/tree spacing.45 P=.2.4 R 2 =23.3% Y=.3+.12X canopy index 3 way analysis of variance (body rots) R 2 =67.4% P= Fitted : logten.ca.mg.k. + no..of.months.sprayed + canopy.index 11

12 2/12/14 Replicated trials 1. Nutrition, canopy management and irrigation 2. Fungicide spray trial 3. Fruit age 4. Lenticel damage vs. Measles Nutrition, canopy management and root health (root health = irrigation + Phytophthora control) R + R + R - R - R + R + R - R - x x x x x x x x xn+ x xn+ x xn+ x xn+ x xn- x xn- x xn- x xn- x x x x x x x x x x xn- x xn- x xn- x xnx xn+ x xn+ x xn+ x xn+ x x x x x x x x Key symbol x R C N explanation Tree Assessed trees C- Root health Canopy management Nutrition Two orchards- organic and conventional C- = no canopy management Dead branches removed from the canopy of all other trees, the lower branches were trimmed to a height of 1 m. 12

13 2/12/14 Nutrition, canopy management and irrigation R + R + R - R - R + R + R - R - x x x x x x x x xn+ x xn+ x xn+ x xn+ x xn- x xn- x xn- x xn- x x x x x x x x x x xn- x xn- x xn- x xnx xn+ x xn+ x xn+ x xn+ x x x x x x x x Key symbol x R C N explanation Tree Assessed trees C- Root health Canopy management Nutrition Two orchards- organic (5-6 yo) and conventional (15- yo) C- = no canopy management Dead branches removed from the canopy of all other trees, the lower branches were trimmed to a height of 1 m. R+ = Root health irrigated treated with phosphorous acid or mulch (organic orchard) N+ = Nutrition Calcium was applied to the ground under trees. 13

14 2/12/14 Results Conventional orchard (trees 15- years old) Factors Body rots Stem-end rots Total rots Tree n.s. n.s. n.s. Box n.s. n.s. n.s. N.4 n.s..2 R <.1 <.1 <.1 C n.s. n.s. n.s. Organic orchard (trees 5-6 years old) Factors Body rots Stem-end rots Total rots Tree n.s. n.s. n.s. Box.5 n.s. n.s. N.5 n.s. n.s. R n.s. n.s. n.s. C n.s. n.s..3 Fungicide spray trial Aims: More efficaceous fungicides Regional differences? Procedures In vitro screening Replicated spray trials 14

15 2/12/14 In vitro testing EC 5 spore germination Fungicide C. acutatum C. gloeosporioides B. parva B. dothidea Phomopsis sp. boscalid <.1 < boscalid/ pyraclostrobin Kocide DS Kocide Champ DP copper hydroxosulphate dithianon <.1 < <.1 fluazinam Everett KR, Owen SG, Cutting JGM 5. Testing efficacy of fungicides against postharvest pathogens of avocado (Persea americana cv. Hass). NZ Plant Protection 58: Everett KR, Timudo-Torrevilla OE 7. In vitro fungicide testing for control of avocado fruit rots. New Zealand Plant Protection 6: In vitro testing EC 5 mycelial growth Fungicide C. acutatum C. gloeosporioides B. parva B. dothidea Phomopsis sp. boscalid > * > boscalid/ pyraclostrobin Kocide DS Kocide Champ DP copper hydroxosulphate dithianon fluazinam * EC5 value is greater than the highest concentration used Everett KR, Owen SG, Cutting JGM 5. Testing efficacy of fungicides against postharvest pathogens of avocado (Persea americana cv. Hass). NZ Plant Protection 58: Everett KR, Timudo-Torrevilla OE 7. In vitro fungicide testing for control of avocado fruit rots. New Zealand Plant Protection 6:

16 mean severity (- scale) fluazanim dithianon boscalid/pyraclostrobin boscalid Biostart Champ DP Kocide 3 untreated -- mean severity (- scale) fluazanim dithianon boscalid/pyraclostrobin boscalid Biostart Champ DP Kocide 3 untreated -- 2/12/14 Field trials 7 Body rots Stem-end rots * * * * 4 2 Treatment Treatment Everett, K.R., Timudo-Torrevilla, O.E., Hill, G.N. and Dawson, T.E. 9. Field testing alternatives to copper for controlling avocado fruit rots. NZ Plant Protection 61: Regional Field Trials 4 orchards per region 4 treatments fruit per treatment 8 applications (March to October) Harvested November Fungicide product 1 Active ingredient Chemical group Rate applied Product/ L Pristine pyraclostrobin/ strobilurin/ 6 g boscalid carboxamide Kocide Opti copper hydroxide copper 9 g Shirlan fluazinam pyridinamine ml 16

17 Rot Incidence (%) 2/12/14 ANOVA Factors SER BR Treatment <.1 <.1 Replicate n.s. n.s. Region <.1 <.1 Orchard <.1 <.1 4 orchards per region 4 treatments fruit per treatment 8 applications (March to October) Harvested November Fungicide product 1 Active ingredient Chemical group Rate applied Product/ L Pristine pyraclostrobin/ strobilurin/ 6 g boscalid carboxamide Kocide Opti copper hydroxide copper 9 g Shirlan fluazinam pyridinamine ml Regional Field Trials 6 a b b b c b b a SER BR Pyraclostrobin/boscalid Fluazinam Copper hydroxide Untreated Treatment Everett, K.R., Pushparajah, I.P.S., Taylor, J.T., Astill, M.S., King, D.B. and Ah Chee, A.. Fungicide spray trial in three avocado growing regions in New Zealand. NZ Avocado Growers' Association Annual Research Report Vol. 8: available on-line at 17

18 stem end rot incidence (%) stem end rot incidence (%) 2/12/14 = inoculated fruit & uninoculated fruit Storage limits of fruit Fruit inoculated with Colletotrichum acutatum Then placed in coolstore (5.5 o C) Week fruit was held at o C and assessed for SER after 1,3, 4, 6 and 7 days After 2 weeks fruit was removed from the coolstore, then every week for 7 weeks The fruit was assessed for SER and firmness on 5 occasions as for day : usually 1,3, 4, 6 and 7 days after removal from the coolstore Weeks in coostorage (5.5 o C) 5.5 o C o C Storage limits of fruit Fruit assessed when hard Fruit assessed when ripe inoculated control Ripeness of 5 by hand inoculated control time in coolstorage (days) time in coolstorage (days) Everett, K.R. & Pak, H.A. 2 Patterns of stem-end rot development in coolstorage. NZ Avocado Growers Association Annual Research Report 2: Dixon, J., Pak, H.A., Mandemaker, A.J., Smith, D.B., Elmsly, T.A. & Cutting, J.G.M. 3 Fruit age management: the key to successful long distance export of New Zealand avocados. NZ Avocado Growers Association Annual Research Report 3:

19 Temperature ( o C) % spore germination % spore germination January February March April May June July August September October % spore germination % spore germination November December January % spore germination 2/12/14 Infection criteria C. acutatum 24hr Everett, K.R. & Pak, H.A. 2 Infection criteria for pathogens causing body rots in avocados NZ Avocado Growers Association Annual Research Report 2: C. gloeosporioides 24 hours Y = 6.75 x (T-).958 x (28.25-T).441 T optimum=25.6 o C R 2 =94.3% P= Y=3.76 x (T-T min ) 1.4 x (T max -T).73 T optimum=23.3 o C R 2 =86% P= Temperature ( o C) B. parva 24hr Temperature ( o C) Temperature ( o C) Phomopsis 24hr Y = 6 1+e -1(x-17) R 2 =46.2% P= Temperature ( o C) 21 C. gloeosporioides Kaitaia Whangarei TePuke C. acutatum Phomopsis sp B. parva 24hr Temperature ( o C) Everett & Pak 2 NZ Avocado Growers Association Annual Research Report 2:

20 2/12/14 What causes measles?

21 water loss (g) 2/12/14 unbagged bagged separate flask fruit

22 2/12/14 Simulate damage Jostle x 22

23 2/12/14.1 mm.1 mm 23

24 2/12/14.1 mm Fungal isolations from measles C.a. C.g. B.p. B.d. P. No isolation Sap. control measles C.a. Colletotrichum acutatum C.g. Colletotrichum gloeosporioides B.p. Botryosphaeria parva B.d. Botryosphaeria dothidea P. Phomopsis sp. Sap. saprotrophs 24

25 2/12/14 Lenticel damage Measles not imbibed not imbibed imbibed imbibed Treatments a not jostled 2.9± ± ± ±1.63 jostled 7.1±1.2.5± ± ±3.58 P values b imbibed(i).47 ns jostled(j) I x J fruit <.1. ns.16 ns ns a Values are means ± S.E.M. for 4 fruit b P values are from a three-way analysis of variance Conclusions Fruit are more susceptible to lenticel damage when imbibed and when damaged Fruit are more susceptible to measles when damaged, but imbibation had no effect Measles are probably due to fungal infection, but lenticel damage is a physical disorder To reduce lenticel damage (in NZ), pick before rainy periods To reduce measles, apply fungicides For both, make sure fruit are treated as gently as possible after harvest Everett KR, Hallett IC, Rees-George J, Chynoweth RW, Pak HA. 8. Avocado lenticel damage: the cause and the effect on fruit quality. Postharvest Biology and Technology 48:

26 % rots 2/12/14 Literature review - Postharvest fungicides Treatment No. of trials % efficacy Flusilazole Permanganate (acidified) 1 58 Prochloraz 55.3 Benomyl Hypochlorite Benzalkonium chloride Thiabendazole % ethanol 2 13 Phosphorous acid Carbendazim Kresoxim-methyl 2 8 Boscalid/pyraclostrobin 1 Everett, K.R. 2 Avocado fruit rots: A review of industry funded research. NZ Avocado Growers Association Annual Research Report 2: Literature review - Postharvest fungicides Prochloraz treatment- apply as soon after harvest as possible Hours after harvest fruit treated Not treated % rots y = 3,1x + 23,5 R² =, Hours after harvest fruit treated Everett, K.R. 2 Avocado fruit rots: A review of industry funded research. NZ Avocado Growers Association Annual Research Report 2:

27 2/12/14 Finally- to reduce postharvest issues Apply fungicides Irrigate the trees and control Phytophthora Apply calcium Apply postharvest fungicides immediately after harvest Minimise handling damage Get fruit to the marketplace as quickly as possible Rationalise the flow of fruit to the marketplace so there are no gluts leading to fruit age problems Gracias muchas Ian Hallett, Henry Pak, Shamini Pushparajah, Olimpia Timudo, Jonathan Rees-George The Organising Committee Bruno Defilippi Raúl Ferreyra Sebastián Rivera Fondecyt WageningenUR Chile 27