By Syb Blythe, Butte County Master Gardener, January 10, 2014
A gall is an abnormal growth produced by a plant under the influence of another organism. Most galls form after insects (tiny Cynipid wasps) lay their eggs in the host plant.
Each gall-making insect forms a gall of a particular size, shape and color; no species forms their galls quite like any other. While commonly-observed oak galls are spherical and woody, some oak leaf galls are horn-shaped, star-shaped, or form tiny jumping galls.
In the wintertime in Butte County, oak galls attached to twigs are perhaps the most commonly seen type of gall. These oak galls (commonly referred to as oak apple galls) form as smooth round balls one to two inches in diameter and range in color from cream and light green to pink, brown and black. They have a sponge-like interior and sit in clusters on the twigs and stems of oak trees. These galls are formed when a tiny gall wasp lays its eggs in the tissue of the oak’s flower buds in the spring. This wasp is one of hundreds of species of gall wasps (family Cynipidae) active in the United States. The tiny wasp also deposits fluids that cause the plant’s cell multiplication process to change, resulting in a gall. The wasp’s larvae develop inside the gall until they are fully-formed adults, at which time they depart the gall through an exit hole.
There are other insects that invade or inhabit galls during or after the residency of the initial gall maker. Some are parasites of gall larvae; others are insects that live harmlessly within the gall (these secondary inhabitants are called inquilines). Birds feed on the growing larvae inside the gall. And galls can be attacked by Phoma gallorum fungi, resulting in dark brown or black galls.
In the summer, an unusual gall to watch for develops on the leaves of mature valley oak trees. This is the tiny gall produced by the jumping oak gall wasp Neuropterus saltatonus. The wasp lays its eggs on the undersides of the oak leaves, leaving discolored spots on the upper sides of the leaves. Galls as small as the head of a pin and resembling mustard seeds develop. Eventually these tiny galls drop from the leaves. Each gall contains a tiny active wasp larva inside. Once on the ground they can be seen moving rapidly and hopping an inch or more high, quite an astonishing sight!
American mistletoe species are native to California and can be found up to 8500 feet in elevation. European mistletoe has been introduced to California and is often seen in Christmas decorations and wreaths.
By David Walther, Butte County Master Gardener, December 27, 2013
Hellebores like high shade and thrive under deciduous trees in well-drained fertile soil. Good locations include the north or east sides of walls, and underneath high-branching trees. Like many flowering plants that do well in shady conditions, hellebores do need light in order to bloom profusely, so the more sun you can provide them in a shady location, the more flowers you will have. While a daily blast of afternoon sun in late summer and fall may scorch their leaves, they will still bloom beautifully in the spring.
An added bonus is that hellebores are deer-resistant and do not freeze in cold winters.
Happy hellebores will self-sow if their flowers (which are actually sepals, rather than petals) are not cut off after the blooms have faded; seed pods will form, eventually (usually in July) dropping their seeds close by the mother plant, where new baby plants will develop. Because the new plants develop so close to the original plant, it is a good idea to thin the babies out or transplant them.
Fertilize in September, when they are forming the buds for their winter & spring flowers.
Right now, when you are raking up leaves and cleaning up your garden, is a good time to cut off last year’s hellebore leaves (most hybrid hellebores are stemless). If there are no buds showing yet, you can simply grab the leaves by the handful and cut them off. If the plant has started to bud, just cut off last year’s leaves. It is not absolutely necessary to do this, as new leaves will cover the old ones, and the old leaves will eventually turn brown and can be swept away by hand. If you are in doubt, it is safe to cut anything (stems or leaves) that has turned brown. Cutting them off does make yard raking easier, as once the leaves are gone you can rake right over the plant. This gives the garden a cleaner look now and also later, when the new leaves and buds appear and the plant blooms.
If you want a hellebore that blooms a particular color, it is best to buy the plant while it is in flower, so you know you are getting exactly what you want. That plant will always bloom that particular color, but there is no guarantee that its seedlings will follow suit.
While some early-blooming hellebores are already in flower, most will bloom between late January and early April. Look for them at your favorite nursery.
By Brent McGhie, Butte County Master Gardener, December 13, 2013
Peach leaf curl, citrus blast and brown rot of citrus fruit are diseases common in Butte County. Fortunately, all three can be prevented or reduced with fall and winter spraying.
Peach leaf curl is a fungal disease affecting only peaches and nectarines. Its distinctive symptoms include the curling, reddening, and thickening of leaves as they open in the spring. Diseased leaves will die and fall off, but are usually replaced by new, healthy leaves once the weather becomes warmer and drier. Still, if this disease is left untreated, defoliation can lead to sunburned limbs followed by borer attacks. Over several years, affected trees may decline and fruit production can be reduced.
To prevent peach leaf curl, trees must be sprayed with a fungicide after their leaves have dropped and they are dormant. This is usually in late November, or December. If it is a particularly wet winter, a second application of fungicide can be made in early spring, just as buds begin to swell. An easy way to remember is to target spraying for “curly leaf” at Thanksgiving and again at Dr. Martin Luther King’s Birthday. Once peach leaf curl symptoms appear (when trees leaf out in the spring) it’s too late for anything to be done to stop the disease. Spraying after symptoms show up is ineffective and removing diseased leaves or shoots will not remedy the problem.
For the home gardener, there are two treatment options. The most effective is the fungicide chlorothalonil (commercially sold as Daconil, Fung-onil, and Ortho Garden Disease Control, among other brands). However, it must be handled with care because it is listed as a likely carcinogen and can cause skin and eye irritation if handled improperly or if protective clothing and equipment (gloves and goggles) aren’t worn. A somewhat less effective treatment is copper ammonium complex sold as Liqui-Cop (a Monterey Lawn and Garden product), or Kop R Spray Concentrate (a Lilly Miller brand). It can be made more effective by applying it with 1% horticultural spray oil in the spray solution. As is the case with all garden chemicals, be certain to read and follow all cautions and instructions on the label.
If you prefer not to spray, you can avoid leaf curl by planting resistant varieties of peaches and nectarines. Resistant peach varieties include Frost, Indian Free, Muir and Q-1-8. Although the Frost peach variety is very resistant to leaf curl, it must receive fungicide applications in its first two to three years of growth. Kreibich is a nectarine variety that is resistant to leaf curl.
Citrus blast damage
Citrus blast and brown rot are diseases that attack citrus trees. Although citrus blast is caused by a bacterium that attacks leaves and shoots and brown rot is a fungal disease that causes fruit to rot and turn brown, both of these diseases can be controlled by spraying with the same copper ammonium complex used to treat peach leaf curl.
When heavy rain, high winds and low temperatures occur together, conditions are optimal for citrus blast, especially on the windward side of the tree. Leaves affected by this disease have a withered, bleached appearance, as if “blasted” by a blow torch. Diseased leaves and twigs will die and occasionally a larger branch can die back. In most cases, fruit production is reduced and the appearance of the tree is adversely affected.
As with peach leaf curl, once the symptoms of brown rot or citrus blast appear, it’s too late to treat them. Both of these diseases are associated with cool, wet conditions, so the best time to spray is before the winter rains begin if you wish to protect navel organges from brown rot, usually mid-October. A second spraying in mid-December and a third in mid-January has been shown to be effective in reducing the severity of citrus blast. For maximum protection, all parts of the tree should be thoroughly coated. The rough texture of mandarin skins can make it difficult to wash spray residue off of fruit. If this residue is not acceptable, an option is to delay spraying until immediately after fruit has been harvested.
Brown rot damage and droplets of gum (left) and brown rot on peach (right)
By Michelle Ramsey, Butte County Master Gardener, November 15, 2013
Both types of bug range from light to dark gray in color and are between one-quarter and one-half-inch long. They are terrestrial crustaceans with a hard shell-like exoskeleton comprised of seven segmented plates. They have three body parts (head, thorax and abdomen), seven pairs of legs and a pair of appendages at the end of their abdomen (called uropods). Their segmented, oval bodies are convex on top but flat underneath. Because they are crustaceans they breathe through plate-like gills located on the underside of the abdomen. These bugs are the only crustaceans that have adapted to living their entire life on land.
Females have marsupial-like pouches on the undersides of their bodies that can hold up to 100 developing eggs. The immature isopod can remain in the pouch for up to 2 months after hatching. Full development to an adult takes about 1 year. During this time, the isopod will molt 4-5 times. Molting occurs in two stages: first the back half of the exoskeleton molts, then, two to three days later, the front half molts. The life span of both pillbugs and sowbugs is about three years.
Sowbugs and pillbugs are most active at night. They spend daylight hours in moist, dark habitats. Because they breathe through gills, they require a very moist environment. That’s why you will find them hidden underneath rocks, in ground litter, or between the edges of moist grass and sidewalk areas during the day. They do not bite, sting or transmit disease. They are harmless to humans.
Sowbugs and pillbugs are omnivores, mainly feeding on dead or decaying plants and animals, and are therefore considered somewhat beneficial in our gardens for their role in overturning soil and producing compost. However, they have been known to feed on tender plant tissue, seedlings, stems and roots of young garden vegetables and other plants.
Sowbugs and pillbugs are not normally pests. However, if control is required, minimize moisture, clean up debris and decaying matter, and water early in the day so the soil dries out by evening. No moisture - No problem!
For more information, visit: http://www.ipm.ucdavis.edu/PMG/GARDEN/FRUIT/PESTS/sowbugs.html
By Marian Stevens and Brent McGhie, Master Gardeners, 11-1-13
Although splitting is not known to result from any single factor, moderate cultural practices that avoid extremes in wet-dry soil moisture cycles and in nutrient levels should help to minimize the trouble. To avoid these fluctuations, trees should be irrigated regularly, especially during hot, windy weather. When hot and/or windy weather is anticipated, irrigate before this weather occurs. Continue to irrigate lightly for a few days, and then resume a normal irrigation schedule. For fertilization, instead of applying a single large application of quick-release fertilizer, smaller monthly applications through the Spring (February through May) may keep nutrient levels constant. Timed-release fertilizers are a convenient way of supplying nutrients at an even rate, but they are more expensive.
Although split oranges are edible, they are usually too green to be usable. Damaged fruit should be removed and discarded, since they may harbor fungi, bacteria, insects and other unwanted pests
Do you have a question for the Butte county Master Gardeners? Call our hotline, at 530-538-7201.
