Fungal diseases in plants are widely classified with distinct features. One such dreadful ailment seen often in rose plant is the Black spots. Diplocarpon rosae fungus is responsible for the disorder that creates black spots initially over the leaves and on due course yellow patches from leaf edges start spreading. On final stage the whole leaf attains the yellow color then eventually crumbles. The disease habitually reduces the efficiency in flowering of the plant. It has been observed that infested plants are likely to acquire winter injury in which loss of flowering buds and leaves are characterized. Minute Spore generating bodies are identified near the spots. These spores start germinating at 65oF in the presence of water molecules and the spreads over the entire leaves as well as cane of the plant.
The cycle of the fungal attack begins from the black spot attack on spore, then the spore gets transported by natural factors like rain and wind, further the spore gets settled over the plant leaves, if it remains until spring month the humidity drives spores to germinate thereby gets propagated to the neighboring plants and starts instilling the leaf parts with Black lesions which on severe; It transforms the color of the leaf into yellow, finally the leaves get disintegrated. If the infection endures the whole winter season it is likely to extend to the adjacent plants easily when there is less spacing provided between the crops. Lesions of purple colors are observed at the stem which on later stage becomes black.
Method of watering is a factor to be considered very vitally in controlling the disease as the growth of the fungus mainly depends on the prolonged moisture content over the leaves. Thus overhead watering is not safe for roses in temperate regions, especially. Another method to control this rose plant disorder will be the use of Organic Neem oil as a strong fungicide to eradicate the fungal growth in the garden. Spraying can be made directly over the leaves for effective reaction against the fungus. Azadirachtin, the fundamental constituent of Neem helps to exhibit the fungicidal property.
In addition, Neem oil also provides a benefit of protecting roses from garden pests since it is well known to repel about most of the pests. Use pure EPA registered neem oil or neem oil having a high concentration of Azadirachtin will be the best product for this purpose.
Author: Adam Teaser - neem
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