bonsaiTALK Community - View Single Post - Boxwood (Buxus) leaves look funny

The symptoms of the leaf spots do not look like those of Macrophoma which is about the only major leaf spot reported on boxwood.

However, leaf spots on plants are not only due to parasitic infections but also by physiological (abiotic) or non parasitic factors. The causing agent of those spots are not always easy to identify because there can be a dozen, or combination, of them that can be implied to cause various types of symptoms on leaves.

It can go from stresses due to temperature, water, light, nutrition, pollution etc. on the plants. This is why we need to know a sort of history of what the plant has gone through to be able to tell which factor or factors could be responsable for the visible symptoms shown on the leaves.

It is always easier to diagnose a disease if we know how the spots are distributed over the foliage : are they only on the older leaves ?, Do the twigs also have spots? Are the spots only on one side of the plant? etc....

From the shape of the spots your picture shows and their distribution over the leaf surface which seems to be mostly between the veins, I would think that is it is a physiological stress as I explained above and I don't think they are very important.

1-Oct-2005	#2
ALDEVAUX bonsaiTALK Master Join Date: Mar-2004 Location: St-Hyacinthe, P.Québec Country: CANADA USDA Zone: 4 AHS Heat Zone: ? Posts: 444	The symptoms of the leaf spots do not look like those of Macrophoma which is about the only major leaf spot reported on boxwood. However, leaf spots on plants are not only due to parasitic infections but also by physiological (abiotic) or non parasitic factors. The causing agent of those spots are not always easy to identify because there can be a dozen, or combination, of them that can be implied to cause various types of symptoms on leaves. It can go from stresses due to temperature, water, light, nutrition, pollution etc. on the plants. This is why we need to know a sort of history of what the plant has gone through to be able to tell which factor or factors could be responsable for the visible symptoms shown on the leaves. It is always easier to diagnose a disease if we know how the spots are distributed over the foliage : are they only on the older leaves ?, Do the twigs also have spots? Are the spots only on one side of the plant? etc.... From the shape of the spots your picture shows and their distribution over the leaf surface which seems to be mostly between the veins, I would think that is it is a physiological stress as I explained above and I don't think they are very important.