Adventures in California History

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Bonnie plant comment

Thought I would pass on an interesting comment I received on my last post, Bonnie Plants Responds? It is from Dave Lambert, and includes some interesting observations. Here is the comment in full. "There is absolutely no doubt that Bonnie is the source of the blight epidemic in many places - this isn’t just the press echo chamber. Here are the facts from Maine: One week before blight was discovered, tomato plants were shipped from Bonnie’s local supplier in Dresden, ME to stores across the state. Immediately after the New York report, blight experts here started checking and found 20% or more of the Bonnie tomatoes diseased at every chain store visited (tomatoes from other sources were clean). The range of symptoms indicated infections 1-2 weeks old, demonstrating disease had occurred in the source greenhouse. At this point, no blight had been found anywhere else in the state, despite widespread and intensive scouting by the extension service and the potato industry. The blight strain isolated from these plants and from subsequent secondary outbreaks in central and southern Maine is US14, rarely found here but common this year in the South. Subsequent scouting around Dresden detected the very beginnings of an outbreak in small organic and other market farms. It was evident that these infections were neither old enough nor abundant enough to be the source of the greenhouse problem. This area has no recent history of blight, but a number of potato and tomato crops have been lost there in the subsequent three weeks. Finally, if Bonnie was so confident of their local suppliers, why would one of their out-of-state representatives have been quoted in a local store just after the initial outbreak saying “You ought to call your Department of Agriculture and have that place (Dresden) shut down”? That said, how might this have happened? I share your opinion that Bonnie’s people are not venal, although much of what they’ve been putting out is somewhat evasive non-denial denials. Not knowing anything specific about their operation, here are several guesses based on 15 years field research with this disease. Frequently removing any diseased plants is a standard and appropriate practice. However, it leaves nothing for inspectors to find. Neither does it arrest the disease. If a single plant is missed or has started to sporulate when it’s removed, you can easilly expect several times as many newly infected plants which will not show symptoms for nearly a week. In this way, the disease can be carried on for months and be shipped anywhere, even if only a single plant is infected. The situation is worse in trucks. The only sure way to eradicate blight, once established, is to clean out the affected section. I suspect that many managers do not appreciate this or might not want to tell their supervisors that a) they’ve let blight into their section and b) all the plants have to be destroyed. Spraying - any new foliage produced between one spray and the next will not be covered and will be susceptible. Coverage is extremely important and will vary with the time between sprays. What fungicide was used? Was it a general protectant with value for Botrytis and seedling early blight or was it a systemic with some kickback more appropriate for late blight? The main points here - blight is extremely easy to tansmit and move around, spraying is helpful but not foolproof, and the best people to detect the disease are those handling the plants - if they are backed up with diagnostic help and managers willing to make hard decisions."

Interesting.