Shake tomato plants to release pollen

We hit a spell of cool weather the past few days. Whenever you get this kind of weather during a hot spell, go out and lightly shake your tomato, pepper and eggplants for about 10 seconds each. Tomatoes in particular have trouble setting fruit when temperatures are above 95 F.

They set during the cooler weather of spring and then stop setting when it is hot. When we get this cool weather they may go ahead and set if they get visits from bees or if the flowers are disturbed. Shaking the plant releases the pollen that bees normally help release by their invasive visits to the flowers.

Even if you have no bees around, shaking the plants may be enough to help them set fruit while it is cool. They will stop again when it gets hot but, if flowers are present, you may get a few to set now if they are disturbed.

Q: This season our lantana has done poorly. For each plant we dig up a bunch of grubs appear. What’s going on?

A: Nice detective work! I would not have guessed this was the problem if you had just sent me a picture of a dying lantana. These guys are decomposers, normally, and people will find them in their compost piles.

But these critters will also feed on small, living roots. In large numbers they can cause a lot of damage or even plant death. In small numbers and feeding on roots, the plant might appear normal with no apparent damage. The dose makes the poison.

Your picture is the immature larva of one of the scarab beetles such as June beetles, metallic June beetles, dung beetles and rose chafers, which we have here. Another one that attacks lawn grasses is the “white grub” or sometimes just called “grubs.”

One very famous and devastating scarab is the Japanese beetle that we have not yet seen in Southern Nevada.

When you find these immature larva feeding in one localized area around a living plant, it is a very good sign they are feeding on it.

They are fairly easy to kill with conventional insecticides such as Sevin used as a soil drench or organically using a treatment of bacterial spores. Bacterial spores are marketed under different trade names but if you look in the insect control section of your favorite nursery or garden center you should be able to find it.

Frequently the bacterial spores are referred to as “milky spore” insecticide. There are also nematode “good guys” that you can apply. I am not sure it is carried in Las Vegas but certainly over the Internet.

Q: I recently purchased the product Tanglefoot for ants around my pomegranate tree. However, after reading the directions it states not to use it on fruit trees. Is it OK or should I get something else?

A: Tanglefoot is a product that can be applied to the trunks of trees and vines. It is like a petroleum jelly or “grease” that stops insects from climbing the trunk using a sticky barrier they cannot cross.

We have used Tanglefoot on fruit trees with no problems. From the manufacturer: “Do not apply directly to young, thin-barked trees or to bearing fruit or nut trees.”

Sometimes Tanglefoot applied to the trunk can cause it to overheat, if it is in the sun, causing the trunk to scorch and girdle it. It can also prevent thin-barked trees from “breathing” through the holes or lenticels in young trunks or limbs.

It can be a problem for young, thin-barked fruit trees, mostly the stone fruits. Apply to older fruit tree trunk and limbs per the label.

Q: I wrote to you about ripening my plums after I picked them from the tree. I did what you told me to do. Why did you tell me to plunge the fruit into cold water after harvesting?

A: Plums will finish ripening very nicely at room temperature after they are picked. We pick them early, when still hard, and do not let them ripen fully on the tree to avoid most of the damage caused by birds.

Birds usually begin “tasting” fruit when the fruit is close to harvest. When we start to see bird damage and the fruit is close to harvest, it is a good indicator that the fruit could be harvested and they will continue to “ripen” off of the tree.

These types of fruit are called “climacteric” since they continue to ripen after harvest. Examples of climacteric fruit are most of the stone fruits such as peach, nectarine, plum and plum relatives such as pluots. Cherries, even though they are stone fruit, will not ripen after harvest.

The speed at which these fruits ripen depends on the fruit temperature; warmer temperatures cause faster ripening. When you harvest fruit in the heat of the summer, the fruit will contain a lot of excessive heat.

This extra heat is from the environment as well as the fruit’s respiration or burning of sugars. We call this heat “field heat.” It can be very destructive to fruit harvested in the field if this heat is not removed very soon after harvest or prevented.

For this reason we try to get the temperature of the fruit lowered as quickly as possible soon after harvesting. You do not want to just put it in the fridge or it will stop ripening.

One way to do this is just plunge the fruit into icy water to remove the field heat and get it closer to room temperature. After it cools to room temperature, you can let the fruit continue to ripen.

Q: I have to take plants growing in the whiskey barrel with a good harvest. This year my eggplant has grown bigger than ever, looks beautiful and healthy and has lots of purple flowers. Since planting it, I’ve only gotten one eggplant.

I get excited but this year it’s just been one giant flower bush. I’ve added nutrients to the soil and it gets enough water, but I don’t know what the problem is. It acts as if it’s going to produce something and yet all I get are flowers. Why is it not producing fruit?

A: I am guessing it is a combination of probably two things: the variety you selected and weather conditions over the past several weeks. Try to stick with a variety of eggplant that has done well for you in the past. I would not just buy any type of eggplant and expect good results. Sometimes when you do that it is just luck.

If you want consistency, year after year, stay with proven winners. Second is the weather. At very high temperatures many vegetables will fail to set fruit. This is because the pollen may become sterile at high temperatures; the unfertilized fruit will start to develop but aborts and falls off.

Some varieties are better at setting fruit at high temperatures than others. I would suggest you mulch the plants. This will help keep soil moisture more constant. If soil moisture goes up and down during the day, the plant may drop flowers as well.

Less likely is a lack of bee activity. I am guessing your bee activity has been about the same as previous years so that it is not likely to be the problem.

I am guessing that if you mulch the plants (try shredded newspaper or unused horse bedding) that they will start setting soon.

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.