There was an interesting article in the Washington Post yesterday by Adrian Higgins about the wet season we are having -- after a multi-year drought, we have already gotten something like 30 inches of rain this year -- and its effect on the garden.
One of the most pronounced effects, which Higgins discusses in some detail, is the prevalence of foliage diseases and fruit rots in wet seasons. We've certainly seen that here: our cultivated cherries had serious fruit rot problems due to the huge, tightly packed clusters of fruit (the smaller, less densely clustered wild sweet cherries along the driveway did not have this problem).
On the subject of foliage diseases he notes that the season for early blight on tomatoes is here and especially bad. I have spent many a year trying to solve the early blight problem, as it is present in virtually all the soils of the eastern US and even the organic sprays to control it are noxious: Bordeaux Mix or some other formulation of copper and/or sulfur. My solution in the past has always been to get the plants up off the ground and use a deep mulch to prevent the spores of this fungus from infecting the plants in the first place. The spores land on a leaft where there is sufficient moisture, especially with a wound, and if the moisture stays around long enough they germinate; next rain (or irrigation) they spash to adjacent leaves and the disease moves up and across the plant. (For an excellent discussion of early blight, see this Cornell website.)
This year I tried something different, or additional, really. I have long foliar fed my plants with a combination of liquid seaweed and fish hydrolysate like Neptune's Harvest or Sea-Plus. But finally the technology has gotten really good for the manufacture of compost teas that have a wide range of "farmed" microbes in them. I'll have more to say about them at some point but for the moment the part that is of interest is their use to restrain early blight.
So for the past couple of months I have been spraying compost tea on my tomato plants after each rain based on the theory that if you establish a rich community of beneficial microbes on the foliage, it will be more difficult for the early blight spores to establish themselves. It seems to have worked like a charm.
If you look at the trellised plants -- where I also did my usual thing of removing all the lower foliage and mulching deeply -- you'll see there is almost no blight. Having that open under-canopy made it possible for me to get the spray head up under the plants and spray upward to coat exactly the foliage that would be first infected because of it proximity to the ground.
Look at the pictures of the determinate paste tomatoes, which, because of the cage that supports them could neither be pruned, not sprayed from underneath, and you'll see that the blight is much more prevalent. And since it spreads by splashing from leaf to leaf, those plants are goners eventually...usually the best one can hope for is to get off a crop before the plants are defoliated, and I think my chances are good on that with these Roma tomatoes.
The biggest problem I have is that because I was mixing the tea (which has no technical fertilizer value) with my usual foliar feed -- and it rained so often -- I am afraid I grossly overfed the plants before realizing a week or two ago that I better stop adding the fish-feed.
Those trellised heirloom indeterminates are a solid nine feet tall and have long since grown off the top of the teepees, fallen back, and then started up again. And while there is fruit, I am sure there is not as much as there will be once the fertility starts to settle down again (too fertile conditions promotes plant growth at the expense of early fruit).
The Roma tomatoes are just as bad/good in that a determinate variety like that shouldn't get to much more than 2-3 feet tall (hence the height of the cage, which is meant to support the fruit) but these are probably a solid five feet already and I haven't seen the terminal shoot yet!
Oh, well! Live and Learn. BTW, The two products I have been using are one called 1-2-3 Compost Tea and one called Bio-Balance. Both of them contain dozens of beneficial bacterial and fungal species. A friend in Vermont, Angie Higuera, has also been testing Bio-Balance as a cutlfower preservative and reports that his customers have been thrilled with its effect on the bouquets they buy.