Bits of information for gardeners. LERP ALERT CITRUS HARDINESS NEW TURF & ORNAMENTAL WEED: GREEN KYLLINGA JAPANESE WHITE BIRCH PESTICIDE STORAGE GUIDELINES WOOD CHIPS: PROS AND CONS PLANT PATENT COURTROOM BATTLE BENEFICIAL INSECT EGGS PHYTOPHTHORA CROWN AND ROOT ROT LERP ALERT — Chuck Ingels, UC Farm Advisor An insect native to Australia and New Zealand that feeds on eucalyptus has appeared in Southern California, the Bay Area, and very recently in San Joaquin County. The people at the UC IPM Program have asked us to watch for it here. The red gum lerp psyllid (Glycaspis brimblecombei) is a sucking insect that causes waxy droppings and defoliation of eucalyptus trees. The psyllid first showed up in Southern California about five years ago, probably brought in unwittingly by a traveler. Outbreaks of the pest have since been reported in several San Francisco Bay area locations. At Stanford University, the infestation was discovered in August 1998 after instructors and other staff members complained that sticky leaves were turning up in campus hallways and lecture halls, tracked in by people's shoes. Up to 90 percent of the leaves on the affected trees there have fallen off. None have died this year, but if they continue to be sucked dry of their fluids by the bug, some may be dead by next summer. The adult psyllid is about 4 mm long with transparent wings and a yellowish brown body. The wings are held over its back in a roof-like position, typical of psyllids. Tiny eggs are laid in batches of 50 to 100 on both new and mature foliage, and nymphs soon begin to produce copious amounts of honeydew. The nymphs are protected by a scale-like covering, called a lerp, which is made from the honeydew. When fully formed in spring, the lerp is about 8 mm long, horn shaped, and tapering from about 0.5 to 4 mm wide and is yellow to pale brown. The eggs, nymphs, and adults can all be found on leaves at the same time. Several generations may occur each year. Research on the biology, distribution, and abundance of this psyllid is being conducted at UC Davis and UC Berkeley. As yet, there are no recommendations for control. A UC Berkeley researcher is planning foreign exploration for lerp natural enemies in Australia during 1999. CITRUS HARDINESS — Chuck Ingels, UC Farm Advisor December’s cold snap reminded us how sensitive citrus fruits are to the cold. This was more than just a frost problem that a simple cover could solve. Most locations had temperatures down to the low 20s for several hours, several days in a row, with occasional 19º readings. Most of the fruit was destroyed, and damage to many trees occurred, but most trees will re-grow this spring. Below is a compilation of the cold hardiness of trees, fruit, and rootstocks. These are not hard and fast temperatures, since damage is dependent on the duration of exposure to cold; also, sources disagree on the exact temperatures and rankings. Meyer lemon (Citrus meyeri) is not a true lemon (Citrus limon); it was discovered in China in 1908 by Frank Meyer. Cold Hardiness of Citrus Varieties (Approx. temperature below which tree damage occurs) Mexican Lime 29° Meyer Lemon 22° Bearss Lime 28° Sweet Orange 21° Regular Lemon 26° Mandarin/Tangerine 20° Grapefruit 25° Kumquat 19° Cold Hardiness of Citrus Fruit Orange Lemon Green 29° Green 28-29° Ripe 27-28° Ripe 29-30° Cold Hardiness of Citrus Rootstocks Standard Semi-Dwarf Dwarf Rough Lemon -low Sour Orange -high Flying Dragon -high Sweet Orange -mod. Trifoliate Orange-highest JAPANESE WHITE BIRCH — Fran Clarke, UC Master Gardener (Betula platyphylla japonica ‘Whitespire’) In the November 1998 Master Gardener Newsletter, I wrote about River Birch (Betula nigra), one of the two birches that has been found to be borer resistant. A roundheaded borer, soon to be joined by the bronze birch borer, is a major problem with other birch trees, particularly newly planted trees or ones that are stressed. The other birch that is borer resistant is the Japanese White Birch, Betula platyphylla japonica ‘Whitespire’. The seeds were collected originally from a single tree in a native stand in the Yatsugatake mountain range, Nagano Prefecture, Japan in 1957. It has proven to be the most borer resistant white barked birch, including other seed strains of Japanese White Birch tested under drought conditions in Longenecker Horticultural Gardens at the University of Wisconsin. The Japanese White Birch has chalky white bark marked with narrow black triangles at the bases of lateral branches. These birches are whiter than the mature European White Birches, which have extensive rough black bark patches at the base. It has a slender pyramidal form, usually growing fast to forty or more feet tall with a fifteen to twenty-five foot spread. Contrary to what many people seem to believe, birches grow best with no competition. The Technical Advisory Committee of the Sacramento Tree Foundation recommends a minimum of fifteen feet between trees and at least ten feet from building foundations. The glossy green leaves are slightly wider and longer than the European White Birch, growing up to three inches long. They turn a clear yellow in fall. Although these trees have been available in the Sacramento area for at least fifteen years, they seem to be relatively scarce in nurseries. The Sacramento Tree Foundation and SMUD have them available for SMUD customers. There is a group of three planted in the front yard at 5715 Carlson Drive in River Park. They were planted in February 1997 when the trees were first offered. They have more than doubled their original height and have been planted at approximately the recommended distances. Unfortunately, I do not know of any more mature specimens in accessible areas. Let me know at (916) 924-8733 ext. 104 if you know about specimens locally. There is a grove of Japanese White Birch at the private Quarryhill Botanic Garden near Glen Ellen in Sonoma County. If anyone has difficulty finding a five-gallon Japanese White Birch, I have permission from our local wholesale grower to give out his phone number: Mike Harlan (916) 725-6461. The tree tags from the Tree Foundation trees do not have the cultivar name of ‘Whitespire’ on them, but they are grown from Betula platyphylla japonica ‘Whitespire’ seedlings. Main sources of information (pictures too!): Plants that Merit Attention, Vol. 1 - Trees and Taylor Guide to Trees. NEW TURF & ORNAMENTAL WEED: GREEN KYLLINGA — Chuck Ingels, UC Farm Advisor Well, OK, it's not that new. But it seems to have spread recently throughout the Sacramento area, especially from Roseville to Rancho Cordova. Commercial turf managers are growing increasingly concerned about this particularly insidious weed, and we don't yet have proven methods of control. Green kyllinga (Kyllinga brevifolia) is a spreading, invasive, perennial sedge that grows best in wet areas in turf and ornamental plantings. It has tough, light green foliage and produces a plentiful supply of seedheads that are green and about 3/8 inch in diameter. It actually doesn't look bad as a turf, except for the seedheads and the fact that it goes dormant during the winter. When left unmowed, green kyllinga can reach a height of about 15 inches. In areas that are mowed, it grows in a prostrate manner, producing a network of numerous rhizomes (the thatch buildup is incredible!). It roots and sends out leaves at each stem node; new plants can be produced from each node if cut off. There's not a lot that can be done to control this weed except hand weeding, mulching in beds, and chemical control. Clyde Elmore and I are conducting a herbicide spray trial in turf in Rancho Cordova. The goal is to kill the weed but not the turf. A new Pest Note has been produced on green kyllinga (Publication 7459) and is included in this mailing. Also available on the IPM website: www.ipm.ucdavis.edu. PESTICIDE STORAGE GUIDELINES Pesticides without proper labeling should not be used. To safely dispose of these containers Master Gardeners recommend the following free services. Dispose of containers at the county/city toxic chemical pickup sites. Flyers with dates and times are distributed with utility bills or can be obtained by calling the City at 264-5403 and County at (916) 363-9390. Contact the Agricultural Commissioners office at 875-6243 for additional information. WOOD CHIPS: PROS AND CONS — Chuck Ingels, UC Farm Advisor Landscapers and arborists often have large amounts of green waste that ends up in the landfill because it is more convenient than taking it to recycling facilities. But they would like to be able to give it away (they’d actually like to sell it!) at closer locations. PROS. Wood chips are like gold – or should be – to many landscapers and backyard gardeners. Wood chips offer the following benefits: suppress annual weeds, conserve soil moisture, cool the soil; enhance root activity in the upper layers of the soil, add organic matter and nutrients, and make a nice walking surface. In the Fair Oaks Demonstration Orchard, weed control is very easy because we’ve put down a 6 to 9 inch layer. Also, we haven’t needed to irrigate yet this spring. Earthworms burrow extensively in the area of the soil/wood chip interface. The chips don’t tie up nitrogen in the soil unless they’re incorporated into the soil. Lastly, the thick layer helps to prevent soil compaction when walking or wheel-barrowing around the root zone. CONS. The use of wood chips does have some drawbacks. There is little published information about problems, so much of the following are only my observations; please let me know of other problems if you know of any. Wood chips can conserve soil moisture to an excess in clay soils, keeping the root and crown area so wet that they rot from soil-borne diseases or simply starve for oxygen. In this case, or where frequent flood or sprinkler irrigation is used, mulch should definitely be moved away from the trunk of sensitive species to dry out the soil; if drip emitters are kept away from trunks, mulch can be placed right up to the trunk in the summer. The mulch also hides the soil, making it more difficult to know when to water. Also, wood chips break down and must be re-applied every year or two. Wood chips can also harbor insects that may attack plants, including slugs, earwigs, sowbugs, and ants. After planting my home orchard, earwigs and sowbugs caused so much damage on the newly emerging shoots that I had to put tree tanglefoot on the trunks (I first used a barrier of masking tape to prevent injury to the trunk), which stopped all midnight snacking by these critters. Some unusual fungal fruiting bodies often appear on the chips, such as mushrooms, bird’s nest fungus, artillery fungus (!), and slime mold, which is also called "dog vomit" fungus for a reason. These are harmless to the soil, although mushrooms can be poisonous and slime mold is pretty gooshy on the feet. Ellen has available copies of a brochure titled, "What is Growing in My Landscape Mulch?" WHERE TO OBTAIN WOOD CHIPS. Wood chips can be picked up for free through S.M.U.D., in the south county on 59th St.; they will deliver a 14 cubic yard load free of charge. Some arborists are more than happy to deliver. In the Fair Oaks orchard and community garden, one arborist has delivered over 20 loads of nice chips. Make sure to ask for clean chips, since some chippers shred rather than chip, and some arborists throw in logs. Coarse, woody chips last longest, while leaves and conifer needles break down quickly. PLANT PATENT COURTROOM BATTLE — Greta Lacin, UC Master Gardener Can genetically altered plants be patented or not? That’s a question that’s about to be weighed in a federal appeals court, and it’s setting off shock waves inside the biotechnology industry. Farming supply dealer Marvin Redenius didn’t start out to challenge such agribusiness giants as Monsanto and DuPont. He bought bags of Pioneer Hi-Bred International Inc. corn seed and resold them to his customers without Pioneer’s permission. For that he was sued. Mr. Redenius and his attorneys intend to argue that plant patents are illegal because Congress doesn’t want the major food crops to be restricted by patents. A great deal of research money and profit is at stake: companies like Monsanto hold hundreds of patents for special lines of crops, and are closely watching the case. Monsanto’s attorneys, meanwhile, believe that the company’s priciest patents are protected because the genes that are transplanted into them are not from other plants, they’re microorganisms. Meanwhile, most Master Gardeners are aware that profiting from reproducing and selling patented plants is a no, no. For now. The full story of this groundbreaking lawsuit was printed in the Wall Street Journal on February 3rd, 1999. BENEFICIAL INSECT EGGS — Janine Jacobs, UC Master Gardener Describe the eggs of these beneficial insects: Ladybug beetle - eggs are laid in groups, yellow in color with an elongate-oval shape, usually laid on the undersides of leaves, arranged on end pointing upright. Praying mantis – eggs are contained within an egg case. The egg case when wet is frothy and beige in color, when dry is has the appearance of hard dry cotton candy that is brown in color. The case can vary in size depending upon the species. Usually found on the underside of a branch or large leaf. Attachment may envelop the entire twig or leaf petiole. Lacewing – 1. (green lacewing) each elliptical, grey-green to green egg is laid o top of a tall filament or stalk. These stalks may be alone or in groups. (species dependant). 2. (brown lacewing) same color, oblong in shape, laid singly and not on a stalk. PHYTOPHTHORA CROWN AND ROOT ROT — Chuck Ingels, UC Farm Advisor Now that the summer is really here, Master Gardeners are getting questions about why a whole tree is suddenly dying or dead. There could be many reasons why whole trees decline, including drought or overwatering, scale or other insects, root or trunk damage, or diseases. When excess water is excessively applied to heavy soils, simple anaerobic conditions can kill roots. But often Phytophthora crown or root rot is to blame. IDENTIFICATION: There are many species of Phythopthora, and all are soil-inhabiting fungi. They attack many different types of plants, and fruit trees are particularly susceptible. The organism requires saturated soil to reproduce and then to infect the host plant; that’s why the disease is usually associated with heavy soils and poor drainage. Symptoms include poor growth, general weakness, cankers, twig dieback, a sparse canopy, and early leaf fall. Almost positive identification can be made by digging some soil from around the trunk and cutting into the bark to the cambium layer. If there is a clear margin of dead tissue just below ground level, with healthy tissue above the margin, it’s probably Phytophthora. PREVENTION: To prevent Phytophthora, adequate drainage must be provided, especially around the crown (the trunk at soil level). If possible, susceptible species should be planted on mounds so that water does not collect around the crown. For a previously planted tree do not add soil around the tree crown to create a mound or create a basin that causes water to settle at the crown area. MANAGEMENT: Sometimes trees showing early symptoms can be saved if the canker hasn’t progressed all the way around the trunk. The technique is to remove a fairly large amount of soil from the area of the crown and upper roots for several weeks or months. This dries the wood and stops the spread of the disease, allowing the tree to recover and develop new conductive tissues. But unless the cause of the problem is remedied (improve the drainage), the disease will be back.