Early blight, also known as Alternaria leaf spot, can
affect plants at any stage of development. All above-ground
parts are susceptible. The most characteristic symptom of early
blight is spreading spots, one-fourth to one-half inch in
diameter, that form on lower or older leaves. These spots have
dark edges, and they are usually brown to black in the center.
The spots frequently merge, forming irregular blotches.
Concentric rings often form, creating a "target" or "bull's-eye"
effect. Affected leaves develop yellow areas around the lesions.
Spotted leaves soon turn yellow, wither and drop off. The fungus
may cause lesions on the fruit around the stem end and shoulder.
The lesion is usually dark brown to black, up to an inch in
diameter and with distinct concentric rings.
Septoria leaf spot can also affect plants at any stage of
development. Numerous small, water-soaked spots first appear on
the lower leaves. These spots soon become circular to angular
with dark margins and grayish centers often bearing one or more
tiny black bodies called pycnidia, which are spore-bearing
structures. Individual lesions are seldom more than one-eighth
inch in diameter and are usually quite numerous on an infected
leaf. Heavily diseased leaves turn yellow, wither and drop off
in large numbers, starting at the base of the plant. Defoliation
can be severe during prolonged periods of warm, wet weather.
As for what to do, here is the checklist: First, keep ripe
fruits picked off the plants. Second, don't work around tomatoes
when they are wet. Next, you can try to improve air circulation,
but if your tomatoes are severely affected, you won't want to
lose any more leaves. And the final step for this year is to try
a fungicide. Mancozeb is probably the recommended one, but it is
very hard to find. The other options are Daconil and maneb,
which are easier to find but probably won't give you as good a
control. The final step for future years is to practice at least
a three-year rotation, with good sanitation in the garden.
Blossom-end rot is a non-pathogenic disease that is very
common during extended dry periods. It also seems to be worse on
tomatoes grown in containers. It begins as a light tan
water-soaked lesion on the blossom end of the fruit. The lesions
enlarge and turn black and leathery. This can drastically lower
the yield and lower marketability of the fruits. The major
causal factors are fluctuating soil moisture supply during the
dry periods and low calcium levels in the fruit.
Control of blossom-end rot consists of providing adequate
moisture from fruit formation to maturity, and use of mulch
(grass clippings, plastic, straw, shredded newspapers or
plastic) to conserve moisture and even out the moisture supply.
Avoid frequent shallow watering. Water deep and then wait five
or more days before watering again.
University of Illinois Extension]