Soft rot disease of potato crops are commonly recognized by soft, wet, cream- to tan-colored flesh, normally surrounded by a dark brown to black ring. fungus quickly grows over the tuber surface and invades, resulting in a moist Left, Photo 1. Sclerotia of Sclerotinia sclerotiorum (0.25 to 0.50 inch in diameter), start out white to cream in color and gradually turn black with age. Davis (emeritus), Plant Pathology, UC Davis. The wilting and dulling of color may happen quickly or over the course of several months. Root rot of sweetpotato generally appears as circular lesions with light and dark brown concentric rings (Figure 1). Fumigants such as metam sodium The fungus then grows out of the senescing tissues onto healthy stems and leaves in the lower parts of the canopy. Sclerotia are usually 0.25 to 0.50 inches in diameter, start out white to cream, and gradually turn black with age (Photos 3 and 4). Aerial stem rot, also known as aerial blackleg, aerial soft rot, or bacterial stem rot can be found anywhere potatoes are grown. In early spring at planting, the bacteria that cause tuber soft rot, blackleg and aerial stem rot are disseminated on infected potato seed (Figure 5). P. erythroseptica(Fig. Initial infections cause stunted growth and yellowing stems. Chemical control. Potato with Scab & Dry Rot at the end Cultural control. and all plant parts can be infected. Host plants in Michigan include alfalfa, dry beans, soybeans, peppers and tomatoes, as well as some common weeds associated with potato production like lambsquarters, pigweed and nightshade. Much of the information on blackleg also pertains to soft rot. This article was published by Michigan State University Extension. Sclerotia require a conditioning period of cool temperatures before they can germinate, but these chilling requirements are easily met during Michigan winters. Planting cold seed into sandy soil may increase the amount of soft rot. carotovora, E. carotovora ssp. Damp rot – penetrates tubers through cuts, scratches, or cracks in the peel that occur when potatoes are affected by various types of scab. yellowing of the foliage. PHI. However, since Sclerotinia sclerotia can survive for several years in the soil, it may be necessary to grow non-susceptible hosts in long rotations to reduce inoculum levels significantly. Stem infection leads to wilting and Michigan State University Extension programs and materials are open to all without regard to race, color, national origin, gender, gender identity, religion, age, height, weight, disability, political beliefs, sexual orientation, marital status, family status or veteran status. Losses typically occur at the end of the season. Since this disease is favored by high humidity and free water in the crop canopy, proper irrigation management is a critical factor in dealing with potential white mold problems. Banks says the stem end and lenticels of a potato open up the door to Pythium when the soil is too warm or too wet. Such potatoes have a greenish tint. Sweet Potatoes with Fusarium Rot The signs of a Fusarium infection, also known as root rot or stem rot, may be seen in the plants in your garden or later in the potatoes that you store. are commercially important seedborne bacteria of potato that cause blackleg, soft rot and aerial stem rot.Dickeya and Pectobacterium spp. Apothecia frequently occur in winter wheat fields that are cropped after potatoes, beans or another susceptible host and wind currents from these fields to neighboring potato fields may carry ascospores. The mycelium generates small spherical sclerotia (about 1–2 mm in diameter) that are white when young and brown when Potato wet rot spreads quickly when stored in a warm and humid room with insufficient ventilation. Stem-end chip defect in potatoes (Solanum tuberosum L.) Yi Wang Under the supervision of Professor Paul C. Bethke At the University of Wisconsin-Madison Abstract Global consumption of potato (Solanum tuberosum L.) continues to shift from fresh potatoes to value-added processed food products such as potato … Ascospores are similar in size to pollen, and when being dispersed by air currents may be caught particularly well by potato blossoms. Click on photo for a larger view. Irrigation strategies that reduce humidity, free moisture in the canopy and allow the soil surface to dry will help decrease white mold. Affected stems on plants surface where infection is initiated. Eventually the rotten tissue turns black. 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