Why are my plants turning yellow? (split from mdvpc's "latest disease" topic)

dice · June 27, 2009

"black powdery stuff":

That should be a major clue. If it was Late Blight, the plants
would probably be dead already. Botrytis is more of gray
color. I do not know exactly what that it is, but it does sound
fungal, some kind of anti-fungal would be a wise choice.

Daconil is basically a preventative. It will not kill fungi already
actively growing on stems or leaves. So you probably want to
continue with the Neem, too.

Here is a report on powdery mildew research on tomatoes.
They did not test any neem oil products, but they did have
some results with sulfur (probably "wettable sulfur" if you
are looking for it at a garden supply or nursery). Sulfur is
probably less expensive than any of the commercial sprays
that they tested. Powdery mildew is one of the fungi that
neem oil is said to do a good job against (black spot on
roses is another).

http://www.hort.uconn.edu/Ipm/veg/htms/pmildtom.html

June 27, 2009	#1
dice Tomatovillian™ Join Date: Jan 2007 Location: PNW Posts: 4,743	"black powdery stuff": That should be a major clue. If it was Late Blight, the plants would probably be dead already. Botrytis is more of gray color. I do not know exactly what that it is, but it does sound fungal, some kind of anti-fungal would be a wise choice. Daconil is basically a preventative. It will not kill fungi already actively growing on stems or leaves. So you probably want to continue with the Neem, too. Here is a report on powdery mildew research on tomatoes. They did not test any neem oil products, but they did have some results with sulfur (probably "wettable sulfur" if you are looking for it at a garden supply or nursery). Sulfur is probably less expensive than any of the commercial sprays that they tested. Powdery mildew is one of the fungi that neem oil is said to do a good job against (black spot on roses is another). http://www.hort.uconn.edu/Ipm/veg/htms/pmildtom.html __________________ -- alias