MEPO Forum :: 園藝

orrfc Wrote:
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> Early blight and Septoria leaf spot infections
> most commonly begin in the early or middle part of
> the growing season but can start at any time.
> Infections can occur anywhere and are most severe
> in wet and humid areas.
> 
> 
> How to identify Early Blight
> 
> Symptoms of early blight typically begin on the
> older, lower leaves of a tomato plant. Over time,
> infections spread upward to newer growth. Early
> blight infections appear as spots that may start
> out circular or irregular in shape. Spots are dark
> brown in color and form concentric rings, or a 
> bullseye pattern, as they grow. The area around
> the infection commonly turns yellow. As infections
> grow, leaves may fall off. Extensive loss of
> foliage is common. Infections most commonly occur
> on leaves but can also appear on stems and fruit.
> 
> 
> How to identify Septoria Leaf Spot
> 
> Symptoms of Septoria leaf spot also start on the
> older, lower leaves of a tomato plant and spread
> upward to newer growth. The spots start out
> circular but change shape as they grow and can
> merge with other spots. Spots typically have a
> dark brown edge with a lighter gray or tan center.
> 
> 
> Small dark spots, the fruiting bodies of the
> fungus, will appear in the gray or tan centers. As
> infections progress, leaves can turn yellow, then
> brown and finally dry and dead. Stems can also
> become infected but infection of fruit is rare.
> 
> 
> How to Prevent and Control Early Blight and
> Septoria Leaf Spot
> 
> Follow the 12 easy steps below to enjoy a long
> season of sweet cherry tomatoes, colorful heirloom
> tomatoes and richly flavored sauce tomatoes.
> 
> Weed your garden. Some weeds, like nightshade, can
> host early blight and Septoria leaf spot and
> spread them to your tomato plants.
> 
> Rotate crop locations. Don’t plant your tomatoes
> in the same place each year. Early blight and
> Septoria leaf spot can persist for multiple years
> in areas where tomatoes were grown.
> 
> Give your tomato plants more space for better
> airflow. At least 2 feet of spacing, more is
> better.Cover the ground beneath your tomato plants
> with mulch, plastic or landscape fabric. A cover
> helps prevent the spread of fungus from the soil
> to your plants.
> 
> Stake or cage plants to keep them off the ground.
> Early blight and Septoria leaf spot can survive on
> stakes and cages. Use only new or disinfected
> stakes and cages. Remove lower leaves for better
> airflow. As plants mature, remove lower leaves
> until there is about 8 to 10 inches of space above
> the soil without any leaves. Do not use overhead
> watering. 
> Avoid getting leaves and stems wet as much as
> possible and avoid watering in a way that may
> splash soil onto your plants. 
> 
> Consider using a soaker hose or drip tape. Water
> in the early part of the day. This allows leaves
> to dry faster. Wet leaves allow fungus to grow and
> spread. Avoid working with plants when they are
> wet. Fungus can be spread more easily when leaves
> are wet. Keep your plants happy and healthy. Weak
> and stressed plants are more susceptible to
> disease.
> 
> Remove and destroy or throw away diseased leaves,
> both off the plantsplant and any that have fallen
> onto the ground. This may help stop the spread if
> caught early enough. If a plant is heavily
> infected, the entire plant should be removed and
> destroyed. Do not put infected leaves or plants in
> a compost pile. Tools used to remove diseased
> leaves should be disinfected before being used on
> a different plant.
> 
> Spray plants to prevent and control the spread of
> Early blight and Septoria leaf spot. Commercial
> fungicides are available. For organic gardens, try
> GreenCure.
> 
> 
> Late Blight on Tomato Plants
> 
> Late blight is another fungus that infects tomato
> plants. It spreads fast and can quickly kill all
> tomato plants in a garden. Once a tomato plant is
> infected with late blight, the entire plant should
> be removed and destroyed. Late blight infections
> first appear as small, water-soaked spots on
> leaves and stems that grow and turn dark brown or
> gray. A white downy growth may develop on the
> underside of infected leaves. Late blight can
> infect all parts of a tomato plant, including the
> fruit. Most of the methods for preventing early
> blight and Septoria leaf spot infections will also
> help prevent late blight infections.