| General Recommendations: Bacterial and fungal pathogens that decay high carbohydrate plant tissue often target fleshy fruit. Fruit spots reflect a delimiting margin of pathogen development into a restricted zone. When many pinpoint infections coalesce, the area may become blighted or, with advancing growth, may decay and rot either on the plant or after it has dropped to the ground. Some of the greatest economic losses are from this group of diseases. The fungal pathogen, Botrytis, is a major fruit spot and rot producer of such crops as strawberry, onion, peach, cherry, plum, pear, grape, pepper, tomato, eggplant, celery, lettuce and carrot. Brown rot of stone fruit affects cherry, nectarine, peach, apricot and almond, causing enormous annual dollar losses on these crops. Likewise, Penicillium blue mold, that we otherwise recognize on stored breads, causes fruit rot of apple, pear, avocado, persimmon, quince and other soft fruits.
Control of Fruit Spots and Rots:
1. Improve air flow and rapid evaporation of free moisture by planting with proper spacing between plants and pruning to open up otherwise dense foliage. Plantings should be positioned so that air flow is maximum and in full sun, depending upon the crop or plant.
2. Apply fertilizers according to a soil test report. Excessive nitrogen application tends to promote more leaf development, which shades the fruit and prevents rapid drying after wet periods. Avoid overhead watering.
3. Mulch plants with clean straw, compost, leaf mold or plastic sheeting to prevent fruit from touching the ground when it falls. Collect and dispose of any fallen, diseased fruit to remove this source of inoculum.
4. Pick fruit frequently and as early as possible in the day or as soon as the plants are dry. Cull out all diseased fruit before storage. Handle soft fruit with care to avoid wounds. Refrigerate promptly at 32 to 50 degrees F.
5. Choose resistant cultivars when available.
6. Spray fungicides to protect blossoms, fruit and leaves from infection every 7 to 10 days depending upon rainfall. |
