Early symptoms of gummy stem blight infection on leaf beginning at leaf tip.įigure 6. Lesions may also consist of circular spots on the leaves.įigure 5. Sometimes the entire margin is affected, creating a brown edge and a downward cupping of the leaf. Leaf symptoms are usually visible at the tips ( Figure 5) as pale yellow or brown dead tissue, often with a yellow halo, extending backwards in a V-shape ( Figure 6). Advanced external symptoms of gummy stem blight. Internal discolouration and rotting of fruit due to gummy stem blight.įigure 4. Narrowing of blossom end of fruit due to gummy stem blight infection.įigure 3. Stem cracks, amber-coloured gummy droplets and tiny black spore-producing bodies at base of cucumber stem.įigure 2. Symptoms become visible mostly during storage.įigure 1. These lesions are soft, wet, sunken, and often contain spots of gummy exudate at the centre. External fruit lesions appear as irregular circular spots that are initially yellow, then grey to brown. If the disease is more severe, the blossom end tapers even more directly to a point and becomes black due to the profusion of fruiting bodies externally ( Figure 4). The brownish-black internal discoloration often extends for 1-2 cm along the length of the fruit. Internal fruit rot is not externally visible and is characterized by a tapering of the blossom end ( Figure 2) and discoloured centrally located tissues ( Figure 3). Fruitsįruits can be affected internally and externally. If seeds are contaminated with this pathogen, damping-off will occur. Such lesions often occur at the base of the main stem, and if girdling by the lesions is complete, wilting and plant death will result. They may also crack and exude a gummy amber-coloured sap ( Figure 1). These lesions become dotted and almost entirely covered with tiny black spore-producing fruiting bodies. Symptoms StemsĮarly symptoms consist of pale brown lesions at wounds created by removing leaves, fruits and lateral shoots. The fungus attacks all parts of the plant, and under favourable conditions, causes severe economic losses. This pathogen infects only members of the cucurbit family such as cucumber, squash, melon, pumpkin, vegetable marrows, bitter melon and zucchini. In Europe, this disease is also called mycosphaerella rot. It is caused by the fungus Didymella bryoniae, previously named Mycosphaerella melonis and M. Gummy stem blight is a common disease found worldwide in greenhouse cucumber.
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