Apply natural pesticides to rid tomatoes of fruitworms

Q: I have Early Girl green tomatoes with round holes in three of them. Otherwise the plant is in great shape. Other fruits on the plant are OK.

A: That is feeding damage probably by the tomato fruitworm. Applications of Bt or spinosad should slow them down and are “organic” controls. Apply these natural pesticides on foliage and fruit.

When you see the much larger hornworms, you can pick them off by hand. You won’t see the fruitworm until you see the damage.

Blacklights or light traps can help show you when these guys are flying and will be a problem in the garden. A light shining against a large white cloth at night is enough to attract them. I will post how to make one on my blog later in the week.

Q: I’m not getting a very big crop of pomegranates this year. My pomegranate trees are about 6 years old. We have a large ash tree in the yard that throws some shade, but the pomegranates get morning sun. I heard they don’t require much water, so I was worried they were getting too much. Then the homeowners association switched from grass to desert landscaping this past year.

A: To produce fruit, pomegranates need at least six hours of sunlight but do best in full sun. As shade increases on pomegranates, the number of flowers and fruits decrease.

Switching from lawn to desert landscaping reduces the overall amount of water pomegranates are receiving. This will affect overall growth, flowering and fruit production.

Pomegranates produce flowers on new growth. If you are getting lots of new growth and there is enough sunlight, there is no reason you should not be getting lots of flowers at that age. The key will be the number of flowers it’s producing. If the tree isn’t producing flowers, of course it can’t produce fruit.

To stimulate flower production, these trees need the same amount of water as other fruit trees. Pomegranate trees are very drought-tolerant but need water to produce flowers. The amount of water depends on the tree’s size. The frequency of watering is the same regardless of size.

A 6-year-old pomegranate tree should be at least 4 or 5 feet across. Its height depends on how it is pruned. An indicator that it is getting plenty of water is the canopy’s density. Your pomegranate tree or bush should be dense enough that you’d have trouble seeing through it.

If you aren’t seeing much new growth and the canopy isn’t dense, this is usually a sign that the tree isn’t getting enough water. Of course production increases if fertilizers are applied as well.

Surface wood mulches help retain water in the soil and improved growth and production of these plants.

Q: My friends are giving me grief because I can’t grow zucchini or other squashes. I get female squash flowers with the squash below the flower. I have male flowers, too.

We seem to have enough insects around to pollinate other plants. The fruit withers at about the size of a large grape. I am thinking that the two flowers aren’t opening at the same time for the insects. What can I do to become one of those zucchini and squash growers who have so many they can’t even give it all away?

A: The recent weather has been strange. Give it a chance to warm up a bit. Summer squash likes warm temperatures.

Zucchini usually produce male flowers first, followed by female flowers a little later. It is possible that they are not open at the same time and having more than one plant should solve that problem.

Bees are needed for pollination. If the plant is very dense, bees may have trouble getting inside the canopy where flowers are. Try removing some of the leaves in the canopy to make it more open so bees can find the flowers more easily.

Some zucchini varieties have a harder time setting fruit when temperatures are high. You might try hand-pollinating. This requires using a soft paintbrush to transfer the pollen from the male flower to the female flower.

You may have a variety that doesn’t do well in our climate. I have one now that I didn’t select and it’s an absolutely lousy producer. It isn’t true that you can pick just any variety and it will do well here because it does well in South Carolina or Ventura, Calif.

Q: I have two 20-year-old African sumacs in my backyard that drop nearly all their leaves every summer. Every fall they always come back. Is this normal? They’re beautiful trees but make a real mess.

A: No, this isn’t normal. Check your irrigation system and make sure it is getting an adequate amount of water. When temperatures in the spring and summer begin to climb, make sure you are increasing the amount of water the tree is getting.

Drought, or a lack of water, will cause leaf drop in these trees. When the demand for water in the fall lessons, they will regrow their leaves.

However, African sumac is a messy tree. There will be a lot of leaf drop and the female trees will drop a lot of berries. The seeds in the berries germinate easily and you may see seedlings popping up all over the place.

Sparrows and mockingbirds love the fruit from the female tree and help to disperse new seedlings all over neighboring landscapes. The male trees produce pollen that is allergenic during the winter months. These are drawbacks to African sumac.

Q: I made the mistake of giving my lawn a minute-long watering at 7 p.m. last summer to go along with its usual watering schedule. I think I got a fungus that destroyed about one third of the lawn. I had been told for years not to water after sundown but didn’t heed that advice.

When we get into the monsoon season with periodic rain during the overnight hours should I treat the lawn with a fungicide before a problem develops?

A: This is why I tell people to never put their lawn to bed at night after an irrigation. If permitted, there is nothing wrong with irrigating around 2 or 3 in the morning but never water immediately after it gets dark and before midnight.

Most diseases need at least six hours of incubation to develop. Our hot-weather lawn diseases prefer warm temperatures and moisture for development. Warm nighttime temperatures and irrigating the lawn as it is getting dark can provide the perfect environment for diseases to develop. When summer monsoons come up from the south, they can raise our humidity enough to make diseases more of a problem than usual.

If your lawn seems to have a disease problem every year, yes, apply an all-purpose fungicide to the lawn and before fungus can develop.

Q: I have a 4-year-old fig tree covered with figs this year. In other years I’ve had a few or no figs on it. They seem to never develop or fall off of the tree.

A: People who don’t have a productive fig tree are nearly always not giving the tree enough water or not watering often enough.

I encourage using wood mulch around fig trees because it conserves water and helps keep the soil moist. Figs will be very productive without wood surface mulch as long as they get enough water and it is applied often enough.

If your fig tree isn’t productive, look closely at how much water you give the tree and how often. Water it the same as you would any other fruit tree.

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.