I have a problem in my tomatoes "Grosse Lisse" the plants were good for about 6 weeks, when the tomatoe plants started to develop heavily crinked leaves the flowers would die and hence no fruit, then I noted that the leaves started to develop yellow to black spots and die off. What would you say this problem could be!!!!! I have tried fungus treatments and tomatoe dust, the soil is rich and they are watered enough!!!!