Several pathogens can cause post-harvest decay of cucurbits, including fungi such as Didymella bryoniae, Sclerotinia sclerotiorum, Penicillium spp., Rhizoctonia solani, Fusarium spp, Phytophthora spp., Pythium spp., and Rhizopus spp. and several bacteria such as Erwinia carotovora subsp. carotovora and E. chrysanthemi. These pathogens have varied life cycles and infection strategies, but infection is often favored by poor production practices in the field (i.e., excessive irrigation and nitrogen fertilization, lack of crop rotation, and poor soil drainage) and wounds created during harvest, storage, and packaging.
Post-harvest decay pathogens cause diverse symptoms. Fungal pathogens may cause a soft, watery black decay of fruit (D. bryoniae), cottony white fungal growth on the surface of water-soaked lesions (S. sclerotiorum), or water-soaked light brown to tan lesions (Rhizopus spp.), among others. Bacterial rots are accompanied by a soft decay of the fleshy root tissues with a watery or slimy consistency as the rot progresses.
No biological control practices have been developed for post-harvest decay in the High Plains.
Practice a three-year or longer crop rotation to nonhosts such as small grains. Deeply bury crop debris after harvest. Avoid reuse of irrigation water in the field and wash water in the packaging shed. Provide adequate, but not excessive, irrigation water and fertilization. Harvest carefully to prevent wounds during harvest and packaging. Store harvest fruits below 50°F and 85 to 90% relative humidity. Thoroughly clean and disinfect bins between storage seasons. If dump tanks are used, use chlorinated water and change water often to reduce pathogen populations. Hot water treatments (1 minute at 135ºF) can provide some control of Fusarium rot. Prompt handling and marketing of cucurbits provides some protection from some post-harvest decays.
Chemical controls must be used in combination with cultural controls to be most effective.
Product List for Post Harvest Decay:
Pesticide |
Product per acre |
Remarks |
Captan |
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|
Captan 50 |
2.5 lb/100 gal |
Dip |
|
Captan 4F |
1.25 qt/100 gal |
Dip |
|
The information herein is supplied with the understanding that no discrimination is intended and that listing of commercial products, necessary to this guide, implies no endorsement by the authors or the Extension Services of Nebraska, Colorado, Wyoming or Montana. Criticism of products or equipment not listed is neither implied nor intended. Due to constantly changing labels, laws and regulations, the Extension Services can assume no liability for the suggested use of chemicals contained herein. Pesticides must be applied legally complying with all label directions and precautions on the pesticide container and any supplemental labeling and rules of state and federal pesticide regulatory agencies. State rules and regulations and special pesticide use allowances may vary from state to state: contact your State Department of Agriculture for the rules, regulations and allowances applicable in your state and locality. |
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Categories: Cucurbits, Disease, Post Harvest Decay, Cucumber, Melon, Pumpkin, Squash, Zucchini
Date: 04/01/2007