Eggplant sensitive to cooler weather

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Question: Will my eggplant plant continue to produce through the fall/winter?

Answer: Although eggplants will keep growing and flowering, they are more productive if cut back and allowed to regrow during late summer. Cut plants to about 6 to 8 inches in early August, cutting them at a crotch and allowing them to regrow.

This means you will need to fertilize again at this time and keep soils moist to force them to regrow and gain size before they begin flowering and setting fruit. The second crop will be ready to harvest about six weeks after cutting back. In Louisiana, eggplants are sometimes trellised and sheared for increased yield and quality later in the season.

The ideal temperatures for eggplant will be 70 to 80 degrees Fahrenheit during the day, and nighttime temperatures between 65 to 70. Obviously, they will produce in temperatures higher and lower than this. Fruit abortion begins at about 95 degrees even though the plant itself can handle heat.

As temperatures get lower than ideal in the fall, eggplant will still set fruit, but fruit set is not as reliable and the development of fruit is slower. Eggplant is generally more sensitive to cooler temperatures than its cousins, tomatoes and peppers. Flowers will consistently set fruit down to 60 degrees nighttime temperatures.

Nighttime temperatures below 60 will mean fewer fruit will be set as temperatures get lower than that. Eggplants begin to get chilling injury at temperatures below 50. As nighttime temperatures get to 50 for extended periods, you might want to consider covering the eggplants at night with a row crop cover. This is a lightweight, woven fabric that will trap heat stored in the soil, raising the temperature below the cover by about 5 to 6 degrees. You then remove it the next day.

Staking may be necessary if plants get big and full of fruit. Fruit touching the ground will spoil. Harvest fruit when they are one-third full size. Over-mature fruit will be spongy, the seeds begin to harden and the fruit surface becomes dull rather than shiny.

Fruit can be snapped off the plant, but they will keep longer if they are cut at the spiny stem, leaving the stem attached. Mulching plants will help to set fruit and improve fruit quality.

Q: Having had several expensive repairs to irrigation pipe necessitated by root damage, I am wondering if you have any suggestions for preventing or lessening such damage. I was told by one sprinkler technician that putting copper (he suggested pennies) in the ground would discourage root growth in the area. Is there any truth to this?

A: I am guessing that the root damage you are talking about is from lifting the pipe from roots growing under the pipes. Roots will not grow into pipes unless there is existing damage to them. The other type of intrusive growth would be in drip irrigation emitters.

The best ways to avoid damage are to bury pipe deep, plant woody plants far enough from irrigation pipe so that it does not become a problem (preferably outside the irrigated zone of the plant) and use the appropriate types of irrigation pipe.

The best way to keep roots from lifting pipe and damaging them is to bury the pipe deep, as it should be. Irrigation laterals (pipe coming from irrigation valves directly to a sprinkler or other type of emitter) should be a minimum of 12 inches deep.

Irrigation lines that are under constant pressure (pipes before the valves) should be a minimum of 18 inches deep. All plastic pipe used for irrigation, when installed after or downstream of the valve, should be a minimum of Class 200 PVC. All pipe under constant pressure (before the valves) should be Schedule 40 PVC.

Class and Schedule refer to the internal pressures that these pipes can withstand, which is related to the thickness of the walls of the pipe. All pipe installed should be "fresh" pipe, undamaged by the sun.

The PVC in most irrigation pipe is rapidly damaged by the sun if left exposed to it. You will see this damage by discoloration of the pipe. In extreme cases, it will turn the PVC black from the damage. Once this damage from the sun occurs, the pipe becomes very brittle and has no capacity for bending. It will shatter easily if bent.

Do not use, or do not let a professional use, PVC pipe that is discolored. Pipe that will be exposed to the sun should be painted or wrapped. Paint will protect PVC from the sun's damaging ultraviolet radiation.

As far as pennies are concerned, this idea comes from the fact that copper is very toxic to plants. Copper sprays are used to control some fungal diseases (Bordeaux sprays). Copper is used to control mildew (which are plants) and algae and mosses (which are plants). Copper will kill plant roots when used as an appropriate pesticide (yes, it is considered a pesticide if it kills plant roots), and copper nails will kill trees if pounded into the trunk a few inches apart.

Perhaps plant roots in direct contact with pennies will be killed, but plant roots just a few inches away probably will not. This would mean that if you were to protect the pipe, you would have to line the pipe with pennies. Even then, expanding roots will still lift pipe, unaffected by the pennies.

Just a side note. Whenever we pound anything into a tree, we need to make sure the damage is minimal. Of course, pounding anything into a tree damages it, but some things are more damaging than others. Zinc galvanized nails will damage a tree more than stainless steel. Whenever anything is put into a tree, it is always best to make sure it is stainless steel if it has to be done at all.

Q: Our peach tree has sap coming out from the ground level to the top of one of the limbs. Not sure if is too much water, not enough water, too many bugs or what.

A: This is the time of year we start noticing borer damage in peach trees. Sap comes out from the limbs and possibly all along the trunk.

A clear indicator of borer damage will be that the bark around the sappy areas will peel off, leaving bare wood under it with clear feeding damage (looks like someone took a miniature sander to the wood in a winding pattern), and if you pull enough bark away, you will see flattened, oval holes from the insects.

You may even see some sawdust under the bark in these sanded areas from their feeding. Remove all loose bark all the way into good wood. You may even find a flattened, ugly larva of a borer just under the bark still feeding. Keep it for a pet if you want to.

If damage is more than 50 percent around the limb, cut it off. Do not paint with black tree wound paint. Paint the trunk and remaining limbs with diluted white latex paint (50/50 with water) on the upper surface of all branches down to 1 inch in diameter.

Borers like limbs and trunks exposed to the hot and intense sunlight. White paint keeps limbs and trunks several degrees cooler than the naturally brown limbs and trunks and helps to reduce damage to these parts from intense sunlight.

Make sure you fertilize in January and water appropriately to keep the canopy dense, shading the limbs and trunk as much as possible.

Bob Morris is a horticulture specialist with the University of Nevada Cooperative Extension.