Tomato Blight & Organic Methods: Hindsight
I've been researching the blight & also this year's weeds via the web, and have concluded that my usual gardening practices PLUS the prolonged wet, cool weather in N. England combined to create perfect conditions for the spread of the fungus in my garden. I don't intend to change my methods much, but I will try to do a few things differently next year.
The recommended organic/'intensive' practices that I use are: 1) growing food plants close together and/or in 'blocks,' 2) mulching w/lots of manure, compost, chicken litter, 3) leaving pulled-up weeds & plant refuse in the garden to add more soil cover & 'biomass'; 4) weeding by hand pulling or with a scuffle hoe (pretty much your only options if you do #1); 5) using cover crops for weed control & soil improvement. I don't use chemical fertilizers, herbicides, or pesticides. These methods produced lush harvests in the past (with virtually no serious pest/disease problems), but this year things went very wrong & I'm trying to understand why. (Of course, w/an airborne fungus I probably would have been hit anyway, but the conditions paved the way.)
I read on one of the university extension sites that wet, humid weather and _poor air flow_ between plants are conducive to blights. Well, I don't thin my rows very much. Since I have enough space, I let indeterminate tomatoes sprawl all over the place, thinking they'll shade/smother the weeds, and all over each other and neighboring crops. (I used to think: why not? You can't have too many tomatoes.) The rich organic layer holds moisture beautifully--too well--and the weeks of rain spawned vigorous, fast growing weeds very early on. They grew fast and thick, with 3/8" stalks and roots that made them almost impossible to pull out by hand. (They are down amidst the plants & have to be pulled by hand w/out pulling up the good plants--if I never slept I couldn't find enough time to get it done.) Of course, the weeds block air flow even more and crowd the good plants. In spring I planted buckwheat and spring wheat as cover crops but the weeds overwhelmed even those. My garden usually looks 'sloppy' 'cause I let weeds & cover crops grow until I want to plant a patch. In normal years, they are not so back-wrenching to pull up or hoe down. The organic advice is even to plant a 'green mulch' like ryegrass in between rows and just mow it during the season.
Maybe if I had been neater, more 'anal' about row spacing and leaving a lot of space around each plant, more would have survived. Reactions from 'neater' gardeners?