Poisonous Plants

As we approach the holidays, there are a lot of questions on poisonous plants. Fortunately, many of these plants have a very bitter taste that limits the amount of the plant eaten. Poinsettia and mistletoe should be kept away from curious children, but the list includes other flowers and plants such as azaleas, calla lily, carnation, daffodil, foxglove, hydrangeas, iris, lantana, narcissus, poppy, sweet pea and tulips. Different parts of the plant may be toxic. Chapter 21 of the California Master Gardener Handbook contains more detailed information as does this poison plant website.

Citrus Bud Mite

Have you ever seen weirdly shaped lemons or oranges that appear to have 'fingers'? The Citrus Bud Mite attacks newly forming flowers and fruits. The mite is only visible with a magnifying glass and has a elongated yellow body with four legs that appear to come out of its head. The mites feed inside the buds, killing them or causing a rosette-like growth of the subsequent foliage and distortion of flowers and fruit. The problem is usually limited to just a few fruit on the tree. Previously recommended oil sprays have not proven effective. This is one of those pests that is best left alone. The oddly-shaped fruit is edible.

Sooty Mold

Aphids, scale, mealybug and whitefly all excrete sticky honeydew that is colonized by sooty mold fungi. By itself, the fungi cannot kill the plant but it can coat the leaves to the extent that sunlight is prevented from reaching the leaf surface. Ants protect the sucking insects from their predators in order to eat the honeydew. Keep ants out of trees and away from honeydew-producing insects by applying a sticky compound such as Tanglefoot on a tape wrapped around the trunk. Trim tree limbs touching buildings, fences or other access points as well. Baits such as ant stakes placed under trees and shrubs may help reduce ant foraging in some cases. A strong stream of water will wash the mold off leaves. The mold can be washed off fruit with mild soap and water. For ant information, see the UC IPM Pest Note on Ants.

Fall Planting

Now is the best time to pull up worn out plants and shrubs and replace them with fresh, healthy specimens. Larger plants such as perennials and shrubs need time to put down roots and settle in before they will bloom well. Here in the Santa Clara Valley, most plants do their growing in the winter with our mild temperatures and regular rainfall. This gives them a head start on surviving our hot, dry summers. Newly planted shrubs will need summer water the first few years, decreasing in amount over time.

Ant Control

The first step is to caulk cracks and other points of entry to the home. One way to control ants in and around structures is to use toxic baits. Baits are formulated as solids or liquids and applied in stations or gels in cracks. Ants are attracted to the bait and carry small portions of it back to the nest where it is given to other workers, larvae, and reproductive forms. The bait toxicant must be slow-acting so enough of it reaches the nest to kill the colony. Boric acid baits are most effective at very low concentrations. Fipronil is a new class of toxicant that is effective against ants at ultra-low doses as well. Make sure you remove any crumbs or sweets from the area, so the bait is attractive to the ants. Refer to the UC IPM Pest Note on Ants.

Powdery Mildew on Apples

Symptoms are leaves and shoots are a powdery white and young growth can be distorted and stunted. The fungus can survive the winter in infected buds. Prune out the diseased twigs during the winter. Look for shoots that are white with flattened, pointed buds. Also remove infected shoots and flower clusters in early spring. Several least-toxic fungicides are available including horticultural oils, neem oil, jojoba oil, sulfur, potassium bicarbonate, bicarbonate of soda (baking soda) and the biological fungicides AQ10 and Serenade. With the exception of the oils, these materials are primarily preventive although potassium bicarbonate has some eradicant activity. Oils work best as eradicants but also have some protectant activity. Benomyl or sulfur (liquid lime sulfur or wettable sulfur) can be used in the spring when the new growth appears as a preventive measure. This also works on scab. See the Pest Note on Powdery Mildew.

Pacific Flathead Borers

The problem appears as a wet sappy area usually on the trunk. Oval holes appear in early summer. The borers attack weakened or stressed trees. Provide proper cultural care to keep trees vigorous and resistant to attack by borers. Protect trees from injuries and prevent sunscald and other damage from abiotic causes. Prune out and dispose of dead limbs and remove dead and dying trees where borers breed. For more information on them, go to the Pest Note on Flathead Borers.

Bulb Planting

Plant in rich, well draining soil.  Soil that has grown annuals or vegetables should be good for bulbs. Dig a hole three times as deep as the bulb's diameter. Mix a tablespoon of fertilizer high in phosphorus and potassium into the bottom of each hole, insert the bulb with the stem end on top and then cover with soil. Soak the area thoroughly.

Figs

Most figs have two crops. The first crop (breba) appears on last year's growth and the second crop on the current year's growth. Figs are a subtropical plant and do best in hot areas but will grow well with some frost protection such as a heat reflective wall. They will tolerate a variety of soil conditions. The varieties that do well in this area are Black Mission, Excel, Grosse Monstreuse, Brown Turkey. Prune fig trees the first year to 3 or 4 structural branches during the dormant season. The object of pruning the first five years is to train the growth upward and outward. Thereafter some thinning of branches and shortening of long shoots is all that is needed to maintain a healthy vigorous tree. Figs can be pruned very hard to keep the tree short enough to reach the fruit.

For a first crop, some varieties bear fruit at the end of the branch, so some full length branches would be desirable. Figs tolerate drier soil conditions so a good soak every 4 to 6 weeks from May to July should do it. If the winter rains are not sufficient, start irrigation in March. During the first year the tree needs only a small amount of a high nitrogen fertilizer or an inch layer of well composted manure within the drip line. Apply in late winter or early spring.  If the tree grows more then 2 feet a year, no fertilizer is needed.

Some common problems with figs are fruit drop, nematodes, and leaf drop. Fruit drop is usually caused by cool weather and can be prevented by planting the right variety. Late season fruit can dry out and drop because of insufficient heat. Nematodes will weaken the tree causing leaves to fall and fruit to stay green. In severe cases the tree will have to be removed. Mites can cause leaves to drop.  Improved irrigation can help. It is natural for older leaves to drop in late summer. Splitting fruit can be caused by high humidity, rain, or irrigation of a dry tree when the fruit is ripening. Harvest fruit when fully matured, firm, well colored, and the fruits bend over at the neck. Remove the fruit with the stem attached.

Flower Pot Cleaning

Dirty flower pots can carry disease in them. Scrub the pot clean with a brush and soak it in a solution of one part bleach to nine parts water for 10 minutes.

Drought Tolerant Ground Covers

These plants survive our dry summers with small amounts of water.  Sea Thrift, Snow in Summer, gazania, sedum, and thymes. Plants and Landscapes for Summer Dry Climates is an excellent resource published by East Bay Municipal Utility District (EBMUD). EBMUD used the following criteria in recommending plants: water conservation, attractive plants that are generally available, minimum pest and disease problems, little pruning or maintenance needs and compatibility with sprinkler systems. The book is available in bookstores and on their website.

Jerusalem Cricket (Potato Bug)

This is one large ugly bug. Up to 2 inches long with very long antennae and shiny amber brown in color withdark brown crossbands on the abdomen. It lives mostly on hillsides under rocks and eats other insects, roots, potato tubers and decaying vegetation. This insect is not harmful, just ugly.

Limes with Stylar End Rot

Usually effects Persian limes but can be on other limes and lemons. Depressed areas are firm or leathery and dry. It starts out looking like a water soaked, whitish-to-drab sunken patch at the base of the stylar tip (end) and can cover 1/4 to 1/2 of the fruit. Inside tissues at stylar end break down and become pinkish or brownish. You can pick before mature to cut losses. Extremely high temperatures can bring it on.

Orange Splitting

Changes in the weather are usual cause. High humidity after a dry period can trigger this problem.  The fruit is edible.

White Fungus In Soil

This is called saprophytic fungus and is not disease causing. The biggest problem is that it's hard to moisten the soil in the area that has the fungus. Breaking up the affected soil is recommended. Using a water penetrant may also be helpful.

Termites

Termites are very common in Santa Clara Valley.  The first sign of infestation may be the presence of winged forms or fecal pellets pushed out of the infested wood.  See the Pest Note on Termites to identify which type is present and the methods of control. Learn all you can before calling in the professionals.

Whiteflies

This pest is common. Sprays usually don't work and reinfestation can be fast. Beneficial insects are very useful for control.  Encarsia wasps have been released to control the Ash Whitefly. The program has been very effective. The University of California is working on a similar program for the common whitefly. Read more in the Pest Note on Whiteflies.