DISEASE MANAGEMENT FOR COMMERCIAL VEGETABLES THOMAS ISAKEIT HORTICULTURE 325 ESSENTIAL MANAGEMENT TOOL: + - DIAGNOSTIC INFORMATION FOR DECISION MAKING KNOWLEDGE! PRE-PLANT DECISIONS SITE-SELECTION SOIL TREATMENT CHOICE OF CROP OR CULTIVAR LAY- OUT OF FIELD / BEDS 1
SITE SELECTION KNOW PREVIOUS DISEASE HISTORY E.G. TEST SOIL FOR ROOT KNOT NEMATODES IF THE SITE HAS A SOILBORNE PATHOGEN THAT CAN BE KILLED BEFORE PLANTING: - FUMIGATION (CHEMICALS OR BIOFUMIGANTS) - SOIL SOLARIZATION SOIL TREATMENT BUSAN / VAPAM APPLIED VIA DRIP IRRIGATION PRIOR TO PLANTING FOR CONTROL OF NEMATODES AND CERTAIN PATHOGENS. 2
SOIL TREATMENT TELONE SHANKED INTO NEW BED IF THE SITE HAS A SOILBORNE PATHOGEN THAT CAN NOT BE ELIMINATED: - CHOOSE A CULTIVAR WITH RESISTANCE TO IT CULTIVAR CHOICE POTATO: RESISTANCE TO VERTICILLIUM WILT 3
IF THE SITE HAS A SOILBORNE PATHOGEN THAT CAN NOT BE ELIMINATED AND THERE IS NO CULTIVAR RESISTANCE: AVOIDANCE CROSS-SECTION OF STEM WITH BROWN XYLEM E.G. FUSARIUM WILT - DO NOT PLANT WATERMELON IN FIELDS WITH PRIOR HISTORY PRE-PLANT PLANNING IN ANTICIPATION OF DISEASE PROBLEMS LATER IN THE SEASON: - CULTURAL MANAGEMENT OF FOLIAR & FRUIT DISEASES CAUSED BY FUNGI - HIGH POPULATIONS OF INSECT VECTORS OF VIRUSES 4
CROP CHOICE -TIME SQUASH LEAF CURL VIRUS ON WATERMELON AVOIDANCE OF VIRUS VECTOR: TIMING OR TRANSPLANTS LOW SPOTS MAY HAVE A MICROCLIMATE THAT PROMOTES DISEASE DEVELOPMENT DOWNY MILDEW PROMOTE AIR CIRCULATION & WATER DRAINAGE LAY-OUT OF BEDS SOUTHERN BLIGHT PHYTOPHTHORA CAPSICI MULCHED TO PREVENT SOIL CONTACT AND / OR RAISED TO PROMOTE DRAINAGE 5
PLANTING DECISIONS CLEAN SEED HEALTHY TRANSPLANTS PLANTING DATE FUNGICIDE APPLICATION TO SOIL CLEAN SEED CABBAGE BLACK ROT SEED CONTAMINATION TOLERANCE: 0.01% FOR DIRECT SEED; 0% FOR TRANSPLANTS INCREASED DISEASE RISK FROM TRANSPLANTS 6
INCREASED DISEASE RISK FROM TRANSPLANTS CRUCIFERS (E.G. CABBAGE, BROCCOLI) - BLACK ROT TOMATO AND PEPPER - BACTERIAL LEAF SPOT - TOMATO SPOTTED WILT VIRUS (THRIPS) - TOMATO YELLOW LEAF CURL VIRUS (WH. FLY) CUCURBITS - GUMMY STEM BLIGHT - BACTERIAL FRUIT BLOTCH - ANTHRACNOSE HEALTHY TRANSPLANTS GUMMY STEM BLIGHT PLANTING DATE WITH NO PATHOGEN (GREEN), 90% WATERMELON EMERGENCE OCCURS AT 20-30 o C, BUT IF RHIZOCTONIA IS PRESENT (RED), DEATH OCCURS AT THESE TEMPS Emergenc ce (%) 100 80 60 40 20 0 12 20 30 35 Temperature ( o C) DELAY PLANTING TO REDUCE DAMPING-OFF 4 3 2 1 0 H:P Grow wth 7
PLANTING DATE EARLIER: TO ESCAPE HEAT-LOVING ROOT ROT PATHOGENS (E.G. Pythium aphanidermatum ON PEPPER) FUNGICIDE APPLICATION PYTHIUM DAMPING-OFF OF CANTALOUP: FUNGICIDES APPLIED IN BAND OR IN- FURROW DECISIONS DURING THE GROWING SEASON FUNGICIDE PROGRAM APPLICATION TIMING & METHOD FUNGICIDE ROTATION PESTICIDE CHOICES WEED CONTROL 8
DISEASE DIAGNOSIS DISEASE DIAGNOSIS DOWNY MILDEW DISEASE DIAGNOSIS POWDERY MILDEW 9
FUNGICIDE PROGRAM #5 CONTROLS POWDERY MILDEW H.P. WM FUNGICIDE PROGRAM 0 = NONE; 5 = BEST; RED = RESISTANCE RISK Relative Control Rating Bact. fruit blotch Downy mildew Powdery mildew Anthracnose Fungicide id chlorothalonil (C) 0 4 2 2 copper 3 1 0 1 mefenoxam (+ C) 0 5 (C2) (C3) myclobutanil 0 0 5 0 pyraclostrobin 0 4 3 5 USE OF PREDICTION MODELS 10
APPLICATION TIMING BACTERIAL FRUIT BLOTCH OF WATERMELON: APPLY COPPER FUNGICIDES AT FLOWERING OR EARLIER APPLICATION METHOD AERIAL APPLICATION IS LESS EFFECTIVE THAN GROUND APPLICATION LATE BLIGHT OF POTATO APPLICATION METHOD - VOLUME OF WATER - NOZZLE TYPE - USE ADJUVANTS (SPREADER, STICKER) 11
FUNGICIDE ROTATION GUMMY STEM BLIGHT ON CANTALOUP FUNGICIDE ROTATION BLACK ROT OF CANTALOUP FRUIT CAUSED BY LACK OF CONTROL OF GUMMY STEM BLIGHT ON STEMS AND LEAVES DUE TO FUNGICIDE RESISTANCE PESTICIDE CHOICES DAMAGE FROM (ILLEGAL) USE OF BANVEL ON CHINESE CABBAGE 12
WEED CONTROL PEPPER MOTTLE VIRUS IN SYMPTOM- LESS WEEDS DECISIONS DURING THE GROWING SEASON IRRIGATION SCHEDULING SANITATION CLIMATE CONTROL HARVEST SCHEDULING IRRIGATION SCHEDULING PYTHIUM ROOT ROT 13
SANITATION GRAY MOLD (BOTRYTIS CINEREA) CLIMATE CONTROL POWDERY MILDEW OF TOMATO: POOR AIR CIRCULATION HARVEST SCHEDULING PHYMATOTRICHOPSIS ROOT ROT MAY APPEAR IF HARVESTING IS DELAYED 14
DECISIONS AFTER HARVEST WASHING STORAGE TRANSPORT MINIMIZE POST-HARVEST DISEASES WASHING DISINFECTANT NEEDED IN WASH WATER TO PREVENT BACTERIAL SOFT ROT STORAGE / TRANSPORT ANTHRACNOSE OF WATERMELON 15