Sap bleeding from tree may indicate borer infestation

Q: About 1/3 of my fruit trees are dying. Some of the branches on a sick tree look healthy; some of the branches on the same tree look dead. There is sap coming from some of the trees. I fear it is a borer infestation. I am scraping the bark and spraying with Neem oil. What do you think?

A: Hard to say without seeing them. There could be several different things going on. Some plants, like plum and cherry, are “sappy.” You can look at them crosswise, and they start to bleed sap. But sap coming from peaches and nectarines can be closely tied to borer problems.

Most plants, if they are healthy — the soil is improved with compost, the soil surface is mulched and the plants watered appropriately — can handle the heat. This being said, our sunlight is intense in the desert, and that can be a problem for fruit trees if they are not protected.

If fruit trees have a lot of sunlight beating down on the trunks and limbs with little protection from the canopy, they can be sunburned, and borers can enter the tree and cause the tree to begin dying, one branch at a time.

Peaches and nectarines, in particular, are not long-lived; perhaps 20 years. Borer damage in peach and other fruit trees normally causes one limb to die, while the rest of the canopy remains healthy. The death of one limb opens the tree to more sunburn problems. This is followed by more borer problems. Eventually, the tree dies from damage created by borers in a couple of seasons.

The only way to tell is by cutting into the sappy areas with a sanitized, sharp knife, and looking for damage created by borers inside the limbs, just under the bark.

Comparatively, if it is a trunk problem, or soil or watering problem, this affects the entire canopy at the same time, and the whole tree, including the leaves, looks bad.

Q: In the spring I replaced all of my sod with a type sold at a local nursery. It looked beautiful, but as summer progressed, it turned progressively browner. It gets plenty of water. The landscaper says it’s brown because it gets too much shade from the Vitex trees. What variety of grass does well in shaded areas throughout the year?

A: Your landscaper might be correct. Lawn grasses will not survive if there is too much shade. The amount of shade that kills lawn grass varies among grasses. Bermuda grass cannot tolerate any shade. Tall fescue is one of the more shade-tolerant grasses. Tall fescue will survive, but not do extremely well, with up to about 50 percent shade.

To estimate the percentage of shade, look at the shade and sunlight patterns created on the lawn at midday. Compare the amount of sunlit areas versus shaded areas. If there are more shaded spots than sunlit spots, there is too much shade for tall fescue.

To increase sunlight on the lawn, remove branches from the tree. It’s easiest to remove the lowest branches first, and that might admit enough light so the grass will survive. Removing the lowest limbs is more of a permanent fix than removing scattered branches throughout the canopy. These branches eventually will grow back. Do this during the winter.

The other option is to use something beneath the tree that tolerates more shade. This option eliminates lawn grasses as a possibility.

Q: My backyard is totally light-colored sand. How should I prepare the soil for planting?

A: You can use the existing sand or soil, and mix it with compost when planting. The compost helps retain water, but still allows for drainage. Compost also “feeds” plants over months as it decomposes.

Dig planting holes five times wider than the container and the same depth as the container. Mix the soil you removed from the hole with at least 50 percent, by volume, compost; one five-gallon bucket of soil mixed with a five-gallon bucket of compost.

Use this compost-sand mixture for planting around the roots of your trees. This is called backfilling. Make sure to saturate the roots with water, along with the soil surrounding them, the entire time you are planting. It’s important not to let them dry out.

After planting, water the planted area three times over a period of several hours, to settle the soil around the plant roots. This helps remove air pockets close to the roots. Build a moat or berm around the plant 4 inches high to hold the water. Watering only with a hose, without this berm, will not get the water deep and saturate the soil around the roots.

Don’t plant too deeply. Planting deeply enough so that wet soil lays against the trunk will rot it. Make sure plants are planted at the same depth as in the nursery containers. If plants are small, they should not need to be staked. Small plants grow faster and establish themselves quicker than larger plants. However, always stake larger plants. Staking is meant to immobilize the roots, not necessarily the top of the plant.

Fertilize plants with compost in January once each year. Use compost rather than a fertilizer because of your sandy soil. Compost helps sandy soils “stick together” better and hold water, but still allows the water to drain.

For small plants up to five gallons, apply one-half to 1 cubic foot of compost to the top of the soil, 12 inches from the plant and circling it. Water it in. Do this even in rock mulch.

If plants are 15 gallon, use 1 cubic foot of compost. The amount of compost needed depends on the size of the plant. Water the compost into the soil with a hose.

Q: I read your article in the LVRJ about replacing a Bermuda grass lawn with fescue. I was going to write you the exact same question! What specific brands of fescue seed do you recommend, and where do I find it?

A: With grass seed, you get what you pay for. Cheap seed is never a bargain when it comes to lawn seed. There are well over 100 varieties of tall fescue available. The same brand of lawn seed changes its contents every year, depending on the price of seed.

It is impossible to list all of the good brand names and seed that might be present in a bag. Instead, pick a bag with at least three types or varieties of fescue mixed in what we call a “blend.” Variety is the spice of life. Mixing several tall fescue varieties, as long as they are the improved types, also blends their advantages.

That being said, avoid pasture types of tall fescue, such as K31, also known as Kentucky 31, and Alta. I call these pasture types of fescue varieties “highway grasses.” Why? Because they look good at 50 miles an hour. They are good tall fescues and have a lot of advantages, but they are not intended for small residential lawns. They look much better when they are planted in parks, green spaces, soccer fields and the like.

Expect between a 25 to 40 percent increase in water use when switching from Bermuda grass to tall fescue. Tall fescue is among the highest of grass types regarding water use. Counteract this increase in water use by making the lawn appropriately smaller. Make the lawn as square or rectangular as possible, and avoid curves or double recurves along the edges. Lawns with curved perimeters are very difficult to irrigate efficiently.

Bob Morris is a horticulture expert living in Las Vegas and professor emeritus for the University of Nevada. Visit his blog at xtremehorticulture.blogspot.com. Send questions to Extremehort@aol.com.