Quote:
Originally Posted by nctomatoman
So the best way to consider this is the absolute definition of resistance and tolerance.
Resistance means that the mechanism of the plant resists attack of the agent - in the case of Fusarium, a fungus that moves into the roots from the soil, a F resistant variety means that the roots resist movement of the agent into the roots.
Tolerance means that even though the agent moves into the plants, the plant can tolerate the attack and do reasonably well for a spell after attack.
But here's the thing - the terms are really relative and misinterpreted. In high disease pressure areas, plants won't resist or tolerate the disease indefinitely. For example, let's say you have a Fusarium resistant plant. The plant will resist the disease a bit longer than a non resistant plant, but if the disease pressure is high, it will go down a few weeks later (or some time frame).
So with grafts, if rootstock is highly resistant to this or that disease, in principal it will from some to alot more time. The key then is to use good garden hygiene, keep soil from splashing onto foliage above the graft line, etc - that plant top will be just as susceptible to the disease as an ungrafted plant - the protection is whatever the roots can provide.
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Very good definition. I have soil rife with fusarium all three races and even the most resistant varieties can sometimes fall to it. The difference with non resistant varieties is that I can have months and months of good production before fusarium finally makes its presence known rather than plants dying before any fruit reaches maturity. This year for the first time I have even had some of my grafts onto RST-04-106-T root stock give in to fusarium recently. However I had several months of fantastic production from those plants but this year has been unusually hot and dry and I think that has stressed the plants more than a normal spring and summer. Added to the stress on the plants was an unusually early appearance of spider mites which further stressed the plants. Even with all the negatives most of my older plants are still producing tomatoes and continuing to grow as long as I can keep the spider mites under some control.
Bill