Brunissure is a name taken from the French which means a browning. The term refers to the effects on the foliage. The first manifestation of the disease is the appearance of irregular brownish spots on the upper surface. The epidermal cells finally slough off, exposing the underlying parenchyma, and numerous white spots appear on the dark background. Ultimately the browning involves the tissues through the leaf and the lower surface is reached. The trouble shows from July to November. As a result of the affection the berries ripen poorly, their sugar content is reduced, the vines fail to mature, and black zones appear in the wood as far down as the roots.
The disease is known in France, where it appeared in the autumn of 1892. It is also known in Italy and elsewhere abroad. Typical cases have been observed in the United States, notably in California. It is destructive only in isolated cases. The disease is thought to affect other plants such as the lily, tobacco, tomato and rose.
The cause of brunissure has not been positively determined. At first it was thought to be due to scale insects, then to a slime mold, Plasmodiophora Vitis (Pseudocommis Vitis). Unfavorable soil and weather conditions have been suggested as possible causes. It is generally agreed at present that the disease is non - parasitic, but this helps but little in disclosing the true cause. Control measures are unknown.
Woods, A. F. Brunissure of the vine and other plants. Science, n. ser. 9:508 - 510. 1899.