GARDENING: Time to watch for lawn disease

This is the time of year when we typically have lawn areas start to get damage from disease and insects coming in from the desert. If you had lawn disease last year you run a good chance of getting it again. You might want to apply a preventive fungicide. Follow the label and use a broad spectrum fungicide that treats a variety of diseases including summer patch or fusarium. If you are planning on putting in winter vegetables then you should be starting transplants soon or buying seeds for fall planting.

Peach twig borer is hitting the stone fruits hard right now, including almonds. Leaf-footed plant bug is emerging and so that means almonds and pomegranates are likely to get hit. You must keep your fallen fruit picked up or they will serve as points of infestation for others. The dried fruit beetle will love to get into your fallen figs and peaches. They will then get into any ripening fruit and ruin them.

We typically see a lot of sunburn on fruits and vegetables this time of year. It is important to try and keep fruit and vegetables like tomatoes with a good canopy cover or cover them with light shade cloth such as about 20 percent shade. More than this might be too much and restrict flowering and fruit set. Apples exposed to the full sun on the south and west side may show signs of sun damage.

Question: Can you tell me how and when to prune a blue chase? It was in a 24-inch box when we planted it in June. It is full of new flowers. We would like it to grow as a tree.

Answer: When you are calling this plant a blue chase I am thinking you mean the Chaste tree or shrub, which can have blue or white flowers depending on the plant. This plant is also called Vitex, Chasteberry, Monk's Pepper, and other names. The species is agnus-castus, which refers to purported herbal uses. It is native to Mediterranean regions and hot Central Asia where it can be found along streambanks.

The plant can reach heights up to about 20 feet and about the same width. The seeds, which smell like pepper and look like peppercorns, germinate readily and can be a problem germinating everywhere there is water. Sometimes the leaves are mistaken for marijuana by excited local children, or even excited adults, which it does slightly resemble.

Like other plants that bloom, the best time to prune it is just after it flowers which will help preserve flowering for the following year. Although I do not recommend it, the plant is used for herbal remedies related to hormonal imbalances and suppression of the libido, hence the name "Chaste Tree."

For more information on the herbal aspects of this plant you can consult the Web site found at www.thorne.com/townsend/oct/herbal.html.

Q: Every year in July, when the grapes are ready to pick, brown voracious insects appear and they hop like fleas. They infest mostly grape leaves but they like vegetable leaves as well. I tried to spray water early in the morning but without control. So before I use any pesticide I would like to know, from you, which is the best way to overcome these criminal insects!

A: I think, from your description, this is the leaf hopper. They are most likely coming in from the desert or abandoned lots with desert vegetation. When the desert plants dry up, they come to your yard, uninvited, for the banquet. Of course those yards closest to these areas are hit the hardest.

We are using a chemical spray for insects called pyrethrum and spraying once a week with it to get some control. It does not destroy them all but keeps them under control. You might also try insecticidal soap to reduce their numbers.

On grapes it is recommended to get levels below 20 insects per leaf. This does not mean you have to try and count these rascals but when you walk by you can get a sense of how many there are. The damage from these insects on grapes is primarily on the leaves. If numbers get too high, fruit can be damaged, usually from spotting on the fruit by excrement but feeding damage could occur at high numbers. Of course, on leafy vegetables any damage is unacceptable.

There are more heavy duty insecticides you can use but you must consult the label for when you can apply and how long you must wait before picking. If your plant is not on the label you cannot use it for that purpose. Try sticking with the more organic controls such as oils early in the year, soaps, pyrethrums, peppermint oil, rosemary oil, and the like.

You can try planting what are called "trap crops" between your garden and the point of entry for the insects. This could be a sacrificial bunch of plants that can be used to keep them from coming much further into the yard. You do run the risk of possibly attracting more into your yard this way but hopefully, if the trap crop doesn't run out, they will help keep most of them contained. We have the same problem at our research site in North Las Vegas where it borders the desert. The rabbits, mostly cottontails but some jackrabbits, come onto the site even though it is fenced on the perimeter. The turfgrass areas are also fenced separately from the perimeter fence and they still get it. You always know they have been there because they leave little deposits where they eat.

On grasses like tall fescue, which has a main that is quite a long stem supporting leaves, once they eat the stem the plant dies. All of the grass plants munched upon then die because they are eaten quite short. It is just like scalping or mowing too short. On other grasses like perennial ryegrass and bermudagrass that can tolerate close mowing, the grass usually recovers if the bunnies are kept off and the area fertilized lightly and watered.

If the bunnies urinate on those spots then the spots die regardless. We have tried the garlic capsules tied to the fence. The garlic serves as an appetizer we found out. We have tried the pepper sprays. We think they prefer either hot Thai or Mexican food. We have considered using a trap crop for them as I mentioned above but are concerned that this might encourage all the relatives.

I know of nothing outside of fencing that will deter these little guys. We did have a coyote or two that used to climb under the fence and had a roundup but I think the recent development out there has been discouraging this predator.

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


<<--[back]