Lack of water thins pine’s canopy

: I have seven, 30- to 40-foot pine trees of various types in my small yard bordering on a golf course and they are surrounded by lawn. I flood my lawn to water them up to the water line but I do not know how often this should be done. Please advise me for various times during the year.

A: If you are watering just your lawn, and doing that carefully by not overwatering, you will not be giving the pine trees enough water. The golf course most likely is not watering the trees very deeply.

If these pine trees are in grass, you could deep water them once every two to four weeks and they would probably be fine. If these trees are not in grass and are in desert landscaping, then you should deep water them about two to three times a week during the hottest part of the summer. In the fall, this could be dropped gradually to once a week. In winter, maybe once every 10 to 14 days.

If pine trees are getting water but not quite enough, the needles will be sparse and you can see sky through the canopy of the tree. If the tree is watered adequately, the canopy will be dense. Of course, this is assuming you are fertilizing once a year in January.

Q: I have three very mature pistachio trees over 8 years old. I have an abundance of nuts every year but the nuts only start to develop and then fall off.

A: The most frequent reason for nut drop in our area is the damage created by an insect known as the leaf-footed plant bug. It has a needle-like mouthpart that it sticks into the kernel causing the nut to drop from the tree.

We generally start seeing this insect on pistachios in late July and in August. Check your tree for this bug. It might still be around. You will need to apply chemicals to control this insect. These bugs also damage pomegranate.

Pistachios trees can be either male trees or female trees. If nuts are produced on a tree, it has to be a female tree. It is possible to have a female pistachio tree that has a male branch grafted on to it. But unless you bought a tree that had this feature, they are all female trees.

I am assuming you have a male pistachio tree or your neighbor has one. If your neighbor has a male tree, it might be close enough to pollinate your trees but it must be fairly close. The further a male tree is away from your females, the fewer nuts will be produced, if at all. I think you will have to solve this pollination problem before you will have nuts. This will require getting a male tree.

Q: My 30-year-old fruitless mulberry tree has a dead branch with this black mold, fungus or whatever it is called on it. Any ideas?

A: This is called sooty canker and is a lethal disease among some trees including mulberry. It is normally spread from infected trees to healthy trees through contaminated chain saws and pruners. Once in the main trunk, the tree will die. Normal control is to cut off infected limbs about 12 to 18 inches below the infection with sterilized pruners or chain saws.

If you need a copy of our publication on this tree disease, e-mail me at morrisr@unce.unr.edu.

Q: I have nematodes in my tomatoes. I solarized my garden area a year ago and it didn't get rid of them. What other recourse do I have to eliminate these pests?

A: Nematodes are a tough one. You tried the right thing. Solarizing will only knock their levels down and then they will repopulate. It is hoped that by solarizing, the levels will be low enough to have minimal damage. Solarizing will never eliminate them.

Try planting varieties that have resistance to root-knot nematodes. Better Boy and Celebrity varieties of tomatoes are a good choice and are resistant not only to nematodes but Fusarium wilt as well.

Gardeners who are interested in trying another approach, might want to consider an organic nematode killer called Clandosan nematicide. Clandosan is a product made from ground crab and shrimp shells recovered as by-products of seafood processing. The ground shells, along with agricultural grade urea, are formed into granular pellets and contain no artificial or synthetic substances, or any product derived from petrochemical sources. I will warn you that it will not eliminate them.

Prior to planting the garden, the product is tilled into nematode-infested soils to a depth of about 6 inches. The Clandosan then acts as a growth stimulus for the multiplication of antagonistic normal soil bacteria and fungi.

After a week or so of feeding on the Clandosan, the "good guy" microorganisms reach high population levels in the soil and need new sources of food. The new food supply turns out to be root-knot and other damaging types of nematodes and within two to four weeks after application, Clandosan is supposed to reduce the root-knot nematode population to nondamaging levels.

However, garden tests indicate four weeks may not be sufficient to reduce nematode populations in areas where root-knot populations have reached exceptionally high levels.

Another possibility is to use composted chicken manure. In some observations of a basil garden, normal applications of chemicals used to control nematodes gave little protection of plants. However, after these failures, the grower incorporated composted chicken manure into the beds and nematode populations declined rapidly. There have been other reports that composted manures had similar results but chicken manure seemed to be the best.

The last resort is to grow short duration crops or plants. Nematodes need about 28 days to complete their life cycle so growing plants that complete their cycle from planting to harvest in 30 days or less also show some promise.

Bob Morris is an associate professor with the University of Nevada Cooperative Extension. Direct gardening questions to the master gardener hot line at 257-5555 or contact Morris by e-mail at extremehort@aol.com.