Dealing With Leaf Problems Of Tomato, Japanese Maple

Q: I have a red leaf Japanese maple and the leaves are withering. The soil is wet, but it acts like it's not getting enough water. What's wrong with my tree?

A: The leaf symptoms of plants that don't get enough water and those that get too much water are indistinguishable. Water uptake by the roots of plants is an active process that requires oxygen, and most plants living in water-soaked soils just cannot access enough water. The foliage then appears to be suffering from drought, even though the soil is wet.

When you water your Japanese maple make sure that you water enough to wet the entire root zone. Watering deeply, but less frequently, promotes deep root growth for healthy trees. Make sure that drainage is good so the soil does not remain wet after watering. Compacted soils from traffic or construction, addition of soil or concrete patios and walks on top of the root zone all restrict adequate water. The leaves will respond with withering and drying around the margins.

Maples planted too close to buildings or paved surfaces are prone to leaf scorch from reflected heat. Overfertilizing maples, especially those planted in frequently fertilized lawns, can suffer from burned leaf edges that appear to be drought-like symptoms. Anything that can promote the health of your tree will increase its ability to withstand attack by diseases and insects. So look carefully at your tree's situation. Study its location, improve drainage, water and fertilize carefully and your maple will give you years of pleasure.

Q: My tomato leaves turn "speckly" early in the season and then dry up later. I have a fungal problem on my onions - is this the same thing?

A: Onions and tomatoes are in two totally different plant families. Plant diseases (and often insect pests as well) seem to like one family or another, so the problems probably aren't related. I can only guess what might be affecting your tomatoes. When lower leaves on my tomato get "speckly," it is due to feeding by flea beetles. They cause lots of tiny holes. These pests don't do enough damage to tomato plants to need control; they don't affect fruit production at all.

If lower leaves or leaf edges dried later, the most likely cause is the summer drought we have had. When your watering is not consistent, you may get some drying leaves. Usually the fruit developing during dry spells will get flat, dark, leathery areas on the bottom. This blossom end rot is a sure sign of drought stress.

Tomatoes are susceptible to several fungus diseases in our area. The most notable are the blight diseases, which wiped out a lot of tomato plants last year about this time. Blight generally starts with small brown spots on leaves and stems. The spots quickly enlarge and the plants can soon look like they were hit by a frost - totally collapsed and dying. Cool, wet weather favors blight development and hot dry weather checks its advance.

We haven't seen much blight this year - knock on wood. It is much more likely to be a problem where the gardener wets the tomato foliage with overhead irrigation.

You didn't describe your onion problem. If you need help with that you may want to take a specimen to your local WSU Master Gardener clinic. To check for the location nearest you, please call Dial Extension 296-3425, tape 112, Master Gardener Clinic Schedule.

Gardening runs Friday in Scene and Sunday in Home/Real Estate. It is prepared by Mary Robson, Master Gardener program director, Holly Kennell, Washington State University/King County Cooperative Extension agent, Susan Miller, integrated pest management specialist, and volunteer Master Gardeners.