Plants prefer wood mulch

Mulches are applied to the top of the soil to help reduce evaporation and weed problems and keep the soil cooler. Wood mulch is an alternative to rock mulch, which also is applied to the soil surface. Wood mulches slowly decompose where the soil is wet, which helps improve the soil over time.

There are a number of plants that grow and perform better when surrounded by wood mulch rather than rock mulch. Many of these plants are in the rose family and include many of our landscape and fruit trees.

Wood mulches should be applied to the soil surface 3-4 inches deep if they are to work well. This type of mulch, which is a very coarse mulch, is best if left on the soil surface and not incorporated into the soil or the root zone of the plants. Soil amendments such as compost are better suited for soil incorporation.

I have made arrangements with the local arborist who has been supplying our wood mulch at the orchard to make this mulch available to the general public. In most cases, this wood mulch is free unless it must be transported long distances; then there may be a transportation cost. Truck load quantities of at least 10 yards would be required. Ten yards will cover approximately 300 square feet with mulch between 3-4 inches deep. Those of you who are interested should call the company’s business office at 564-1998.

Q: I have some zucchini plants producing zucchini that get only 2-3 inches long, turn yellow and brown and then rot.

Also, I planted my corn too close together and got a few empty or half-empty ears but the plants are covered with a gazillion small black bugs. I think they are bugs even though they don’t seem to move. How can I avoid them next year?

A: All summer squash, such as zucchini, straightneck or crookneck, pattypan or scallop types, require pollination from the male flowers. Summer squash are unusual because they produce both male and female flowers on the same plant.

The first flowers are usually male and will not produce fruit. After a short time, female flowers are produced and pollen from the male flowers must be transferred to the female flowers for the fruit to mature. Bees are responsible for transferring this pollen.

In some cases, these fruit will grow a short time without being pollinated but they fail to develop. The condition you are talking about typically results when the pollen is not successfully transferred to the female flower.

If temperatures are very high, this might interfere with pollination because the bees are busy hauling water to cool themselves or it is just too hot for good pollination. Some light shade may help.

If you see no bees, you might have to hand-pollinate the female flowers. You can do this with a delicate paintbrush or take the male flowers off of the plant and put the pollen directly on the female portion of the flower. Flowers open in the morning and are good for only one day.

You will need to pick summer squash nearly daily if you want soft, succulent fruits. Zucchini should be harvested when they are 6-8 inches long. If you let them become too large, they will begin to suppress the development of new fruit. It is important to keep these plants harvested.

I am not sure what is going on with your corn and you should be able to tell if these are bugs or not with a magnifying glass. The only insect I can think of that might be a problem on corn is the corn leaf aphid, which you should be able to get rid of with soapy water or insecticidal soap. If you want a harsher, but still organic insecticide, try pyrethrin or rotenone sprays or dusts.

Q: We have hedged privets and pink hawthornes across the front and back of our house. They are about 10 years old and have a lot of dead wood in them. We were told that the life span of most shrubs is only 10-12 years in our Las Vegas climate. Before we give up on these shrubs, we were wondering if cutting them back a lot in the fall would help them survive.

A: It is true that many plants have a limited life span but it is not due to our climate. It is mostly due to putting plants in locations where they are not supposed to be because they are too large and do not fit. For this reason we constantly cut them back to make them fit and then they get too woody.

In this particular case, even though you did not tell me, I suspect they are in a rock landscape. In this type of landscape, they usually do not get the right nutrients (even though we fertilize them) so they begin to yellow and then become sparse and woody. Hawthornes in particular will not do well in the long run in very hot locations.

As their general health deteriorates, they will do even worse in these locations. The healthier the plants are, the better they can handle adverse conditions. At some point they start into a death spiral.

At this point, I am assuming your plants have been in poor health for quite some time and it will be difficult, but not impossible, to get them to recover. If you do not want to replace them, then you can start a fertilizer program, cut them back and try to force them into recovery.

The fertilizer program can begin this fall, but do not expect any big improvements until next spring. When temperatures begin to get cooler, try using some organic fertilizers around these plants along with some iron chelates applied to the soil.

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 morrisr@unce.unr.edu.