When is enough, enough? Timing of the final fungicide application on tomato fruit rot severity

Transcription

1 When is enough, enough? Timing of the final fungicide application on tomato fruit rot severity Cheryl Trueman, M.Sc. 3 th Annual Tomato Disease Workshop Baton Rouge, LA October 5-6, 215

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3 JANUARY FEBBRUARY MARCH APRIL MAY JUNE JULY AUGUST SEPTEMBER OCTOBER NOVEMBER DECEMBER

4 Fruit Rots in Ontario Anthracnose (Colletotrichum coccodes) is the primary rot Others include black mould (Alternaria spp.), buckeye rot (Phytophthora spp.), etc.

5 Fruit Rots in Ontario Problems are exacerbated by: Premature defoliation (bacterial spot) Harvest delays due to heavy rainfalls Abnormally warm temperatures in late Summer and Fall

6 Current Management Practices Regular applications of fungicides beginning at early fruit set Chlorothalonil and azoxystrobin most common Some growers continue application up to harvest Is there value in this? Especially with limited early blight and/or Septoria leaf spot disease pressure

7 Research Questions 1. How long should fungicide programs continue before harvest, and does optimum timing change if there is a harvest delay? 2. Is the optimum timing for the last fungicide application different for a chlorothalonil fungicide program compared to an azoxystrobin alt. chlorothalonil program?

8 Experimental Design One trial completed in 213, 214, and 215 Ridgetown Campus, University of Guelph Processing tomato cv. H999 Split-split plot design Main plot: 1. Fungicide program: a) Chlorothalonil b) Azoxystrobin alt. chlorothalonil Nontreated control plots also included for each harvest timing. Sub-plot 2. Harvest timing: a) On-time b) Delayed Delayed harvest transplanted 1-14 days earlier than on-time, harvested same day. Sub sub-plot 3. Final fungicide: a) 7 DBH (7-8 apps) b) 14 DBH (6-7 apps) c) 28 DBH (4-5 apps) DBH = days before harvest

9 Early planted, delayed harvest Late planted, on-time harvest

10 Harvest Assessment Picked all fruit in 1 m of twin-row (~1.5 m 2 ) Reds, breakers, greens, and field rots Fully red fruit sorted into healthy, anthracnose, black mould, and other basket rots Year Ripe (%) At Harvest On-time harvest Delayed harvest a Ripeness was calculated by dividing the sum of reds and field rots by total yield.

11 Data Analysis 1. To determine if fungicide treatments were different from nontreated control (for same harvest timing only), SAS 9.4, proc mixed. Dunnett s test Contrast analysis for fungicide programs 2. To determine effects of fungicide program, final application timing, and harvest timing ANOVA in proc mixed, data from different factors combined with ANOVA revealed no significant interactions

12 Incidence (% by weight) Anthracnose Black mold Other basket rots All harvested rots Yield (kg / 1.5 m 2 ) Normal Harvest Control Chlorothalonil 213 Delayed Harvest Anthracnose Black mold Other basket rots All harvested rots Healthy reds Total reds Breakers Greens Field rots Total Healthy reds Total reds Breakers Greens Field rots Columns with a star are significantly different than the other column in the same group, P.5. Total

13 Incidence (% by weight) Yield (kg / 1.5 m 2 ) Normal Harvest Control Azoxystrobin alt. chlorothalonil Anthracnose Black mold Other basket rots All harvested rots 213 Delayed Harvest Anthracnose Black mold Other basket rots All harvested rots Healthy reds Total reds Breakers Greens Field rots Total Healthy reds Total reds Breakers Greens Field rots Columns with a star are significantly different than the other column in the same group, P.5. Total

14 Effect of fungicide spray programs on the incidence of tomato fruit rots in processing tomatoes harvested on time, or delayed, Ridgetown, ON, 213. Incidence (% by weight) 6 Chlorothalonil Azoxystrobin alt. chlorothalonil 4 2 Anthracnose - delayed Anthranose - on time Black mold - delayed Black mold - on time Other rots All rots - delayed All rots - on time Numbers in a column followed by the same letter are not significantly different at P.5, Tukey s adjusment. Data from different factors was combined when ANOVA revealed no significant interactions (P.5).

15 Effect of timing of the final fungicide spray on the incidence of tomato fruit rots in processing tomatoes, Ridgetown, ON, 213. Incidence (% by weight) 6 7 DBH 14 DBH 28 DBH 4 2 a ab b Anthracnose - delayed - chl. Anthracnose - delayed - azo. alt chl. Anthracnose - on time a ab b Black mold - delayed Black mold - on time Other rots All rots - delayed All rots - on time Numbers in a column followed by the same letter are not significantly different at P.5, Tukey s adjusment. Data from different factors was combined when ANOVA revealed no significant interactions (P.5).

16 Effect of different fungicide programs and timing of the final fungicide spray on yield in processing tomatoes treated with chlorothalonil or azoxystrobin alt. chlorothalonil, Ridgetown, ON, 213. Numbers in a column followed by the same letter are not significantly different at P.5, Tukey s adjusment. Data from different factors was combined when ANOVA revealed no significant interactions (P.5). 2 Yield (kg / 1.5 m 2 ) Chlorothalonil Azoxystrobin alt. chlorothalonil 7 DBH 14 DBH 28 DBH Total Total

17 Yield (kg / 1.5 m 2 ) Incidence (% by weight) Normal Harvest Control Chlorothalonil Anthracnose Black mold Other basket rots All harvested rots 214 Delayed Harvest Anthracnose Black mold Other basket rots All harvested rots Healthy reds Total reds Breakers Greens Field rots Total Healthy reds Total reds Breakers Greens Field rots Columns with a star are significantly different than the other column in the same group, P.5. Total

18 Incidence (% by weight) Normal Harvest Control Azoxystrobin alt. chlorothalonil Anthracnose Black mold Other basket rots All harvested rots 214 Delayed Harvest Anthracnose Black mold Other basket rots All harvested rots Yield (kg / 1.5 m 2 ) Healthy reds Total reds Breakers Greens Field rots Total Healthy reds Total reds Breakers Greens Field rots Columns with a star are significantly different than the other column in the same group, P.5. Total

19 Effect of different fungicide programs and timing of the final fungicide spray on fruit rot incidence in processing tomatoes treated with chlorothalonil or azoxystrobin alt. chlorothalonil, Ridgetown, ON, 214. Numbers in a column followed by the same letter are not significantly different at P.5, Tukey s adjusment. Data from different factors was combined when ANOVA revealed no significant interactions (P.5). Incidence (% by weight) 6 Chlorothalonil Azoxystrobin alt. chlorothalonil 4 2 a b 7 DBH 14 DBH 28 DBH Anthracnose Black mold All harvested rots - on time All harvested rots - delayed Anthracnose Black mold All harvested rots - on time All harvested rots - delayed

20 Effect of different fungicide programs and timing of the final fungicide spray on yield in processing tomatoes treated with chlorothalonil or azoxystrobin alt. chlorothalonil, Ridgetown, ON, 214. Numbers in a column followed by the same letter are not significantly different at P.5, Tukey s adjusment. Data from different factors was combined when ANOVA revealed no significant interactions (P.5). 2 Yield (kg / 1.5 m 2 ) Chlorothalonil Azoxystrobin alt. chlorothalonil 7 DBH 14 DBH 28 DBH Total - on time Total - delayed Total - on time Total - delayed

21 Preliminary Conclusions Applications of chlorothalonil (213, 214-delayed) and azoxystrobin alt. chlorothalonil both reduced the incidence of harvested fruit rots versus the controls. Yield benefit in 214 for both programs In most cases, no difference in disease reduction or yield among programs. Continuing fungicide applications up to 7 or 14 DBH provided no additional benefits compared to ending applications 28 DBH.

22 Future Work / Considerations Analysis of 215 field data Very low fungal foliar disease pressure in 213 and 214, but Septoria leaf spot present in 215. Ending fungicide applications 28 DBH may put the crop at risk from late blight.

23 Acknowledgements Ontario Tomato Research Institute Ontario Ministry of Agriculture, Food, and Rural Affairs Ridgetown Campus, University of Guelph Phyllis May, Marianne DeBruyn, and summer research assistants.