Yellow Foliage can imply an incorrect pH

I have noticed more yellow birch foliage recently than I recall seeing at one time. It is caused by too much lime or calcium.

A pH too high for birch will cause the veins to be a darker green. Birch do not like as much lime as many of our common nursery crops. The calcium can come from limestone gravel or runoff from a gravel road.

What I have seen is on younger trees. The color may be greener next year when the roots get a little deeper below the lime. Lime can be countered with sulfur. A soil test will determine the pH and confirm my suspicions.

Many leafspot diseases are caused by fungi during wet, rainy spring weather. The disease will usually shut down when the weather changes. But the spots remain on the older, lower foliage. The newest growth will have no spots.

There is no reason to spray now if this is the situation. Spraying will not remove the spots on the older leaves.

Some problems are merely cosmetic and require no spraying. There is no reason to get upset and spray for problems that are not problems.

Anyone planning to ship into areas without the Jap. beetle must properly treat or dip. The Discus treatment must be applied in May, June or July. Check with your nursery inspector. Call me to check your sprayer output and figure how much Discus is required per tank.

The stress caused by the extreme heat and dry conditions has caused some more December cold injury to show up on a few arborvitae. The upper third to two-thirds of a few Dark Greens are turning brown branch by branch. I exposed the main stem and found (busted bark) splits in the bark. The block was in a low area where cold air would settle.

I also found a few two spotted spider mites and Broad mites last week under poly. The symptoms of Broad mites is similar to light 2,4-D injury. The spider mites suck the chlorophyl from individual leaf cells and the appearance is stippled, but also with a grayish or metallic appearance.

I found the spider mites with white paper and a hand lens. I found the Broad mites and their eggs with a microscope.