Here’s a great tool offered from the Texas AgriLife Extension Service, Texas A&M System. This is a great pictorial tool for tomato problems. Just click on the link (or copy and past).
http://aggie-horticulture.tamu.edu/publications/tomatoproblemsolver/
The website also has a guide for cucurbit problems. I suggest you browse the site for other sources of information.
Monroe County Master Gardener Association 
Thanks so much for the link. Another good i.d. tool for our arsenal.
Texas A&M has a terrific extension program…and this site is typical of the quality of their articles. I came upon Tamu when doing research for our blog.
Another interesting factoid is that the Junior MG program was developed at Texas A&M… and this is what Jennie suggested to Sharon be the basis for her ISD greenhouse class. Infact the only Junior MGs in the county are graduates of this program.
GB is right…we should put together a list of “must go to” sites that give the best information for our gardening problems. I am fortunate in that Jennie has shared some of her favorite sites with me…so I guess this will be my winter project to post them.