We must really love tomatoes. Even with farmer's markets, CSAs, and farm stands loaded with fresh, locally-grown tomato fruits this time of year, we still insist on growing our own. This is even more impressive considering all the problems tomatoes can have.
White flies are easy to kill with insecticidal soap. Blossom end rot is not a disease or insect, but a calcium deficiency caused by fluctuating soil moisture levels. Simply mulch, water regularly and blossom end rot goes away.
The biggest problem facing tomatoes is foliar diseases. They carry ominous names such as Septoria leaf spot, bacterial speck, early blight, and the dreaded late blight. These diseases can quickly turn a dark green, leafy plant into a brown mess.
So, what to do?
First: mulch. Many diseases are soil-borne, and during rain, disease spores can splash onto the bottom leaves and infect the plant. Mulch slows the onset of disease. Pick off spotted and yellowing leaves as they form.
Compost these leaves, except for the late blight, which the whole plant should be bagged and removed. Spray organic fungicides, such as Serenade or copper, to slow the disease spread. Next year, grow disease resistant varieties, such as Defiant and Mountain Magic, and grow tomatoes in containers.