- Author: Belinda J. Messenger-Sikes
- Author: Karey Windbiel-Rojas
Like outdoor plants, houseplants can also experience pest problems. Did you know that too much or too little watering is the most common way that houseplants die? They can also suffer from too much or too little light, incorrect fertilization, and a variety of pests and diseases. Knowing the proper growing conditions for your houseplant and checking regularly for signs of pests or disease are the best ways to keep your houseplants healthy.
If your houseplant is looking unhealthy, our newest publication Pest Notes: Houseplant Problems can help you find out what may be wrong. Authored by UCCE Environmental Horticulturalists Dennis Pittenger and Donald Hodel, this new resource can help you narrow down the cause of a plant problem and decide what actions to take. If you find . You'll find sections on many common pests like aphids, mites, and mealybugs as well as leaf spots, wilting, or other disease symptoms. Once you've figured out the problem, you will also be able to find out how to manage to manage it use less toxic methods.
If you have feedback on this or other Pest Notes publications, let us know what you think by filling out this quick, anonymous survey.
- Author: Dennis Pittenger
[From the August 2015 issue of the UC IPM Green Bulletin]
A. Landscape irrigation accounts for only about 9% of total statewide developed water use, but the percentage varies widely among communities. Water applied to landscapes is estimated to account for about 50% of residential water consumption statewide, but the amount varies from about 30% in some coastal communities to 60% or more in many inland suburban communities.
Q. Does a landscape have to be re-planted with specific drought resistant, native, or California- Friendly plants to save significant amounts of water?
A. No. Field research studies indicate that traditionally used landscape trees, shrubs, and groundcovers have considerable drought resistance and perform acceptably with about 40% to 60% of the water required to maintain the average lawn in good condition. This is comparable to the water required by so-called drought resistant, California Friendly, and native plants to perform acceptably in landscapes. The common perception is that plants traditionally grown in landscapes are not drought resistant, so they are usually over watered.
Q. How much water can be saved by removing a lawn?
A. Water savings depends on how effectively the lawn has been irrigated, the type of turfgrass removed, which plants and how many will replace it, and how effectively the water applied to new plants is managed. If a lawn is removed and plant material is changed but the irrigation system and water management practices are not improved, then little water savings will be realized. If the lawn has been over watered and irrigation was poorly managed, then maximum water savings are possible by removing the lawn. However, in such situations keeping the lawn and simply improving irrigation management and improving or replacing an inefficient irrigation system will also generate substantial water savings without the trouble, cost, and the loss of aesthetics and functions that occur when removing the lawn.
A. As with lawns, it depends on the amount of water currently being applied. Plantings that have been maintained with high soil moisture content can usually maintain acceptable performance with a 20-40% reduction in irrigation by extending the interval between thorough irrigations as described above. Additional 10- 20% irrigation reductions to theses plantings or to plantings that have already been irrigated below optimum will usually allow plants to remain functional, but they will grow less, possibly wilt and drop some leaves. It is important to gradually reduce water over a few to several week period by extending the interval between irrigations and applying enough water to wet most of the root system at each watering.
A few deep, root-zone wetting irrigations spaced 3 to 6 weeks apart from spring through fall can be enough to keep most trees and shrubs alive when water is in short supply. Many tree and shrub species will drop leaves, wilt, or suffer dieback of some branches under severe water shortage, but will survive.
Q. When should trees, shrubs, and other landscape plants be planted in a dry year or if drought is expected?
A. Hold off planting until fall or winter to take advantage of cool weather as well as fall and winter rains. The planting site may be prepared in spring or summer, however.
To access this article in it's entirety, see the August 2015 issue of UC IPM's Green Bulletin or visit the UC Center for Landscape and Urban Horticulture
- Dennis R. Pittenger, Area Environmental Horticulturist, UC Cooperative Extension Los Angeles County/UC Riverside, dennis.pittenger@ucr.edu
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- Author: Donald R. Hodel
- Author: Dennis Pittenger
Victorian box (Pittosporum undulatum) is an evergreen tree native to Australia that grows moderately fast to about 50 feet high and wide. It was much planted as an ornamental landscape subject in the first half of the 20th century in coastal central and southern California, especially from Santa Barbara to San Diego, where it was used as a lawn or street tree, background, screen, or informal hedge, and prized for its dense canopy, attractive and glossy green foliage, fragrant white flowers, showy orange fruits, and ease of cultivation (Figure 1). Indeed, from late January through March, especially in the evening, one can detect the wonderful, sweet, somewhat citrus-like fragrance of its flowers wafting through the air in older neighborhoods. Victorian box has somewhat fallen out of favor as a landscape subject in the last 40 years but is still found in nurseries and as old and young plants in the landscape. Typically a vigorous grower, trunks can attain one to two feet in diameter; and the tree can produce copious amounts of fruits, which readily germinate and produce seedlings in irrigated landscapes.
Over the last 25 years, arborists, horticulturists, landscape managers, and others have frequently noticed a widespread decline of older, established Victorian box trees in Southern California. Affected trees tend to lose vigor gradually but steadily; canopies thin; leaves yellow, die, and drop; and twigs and branches die back, either generally over the whole tree or, at least initially, restricted to one or more branches (Figure 2).
The exact cause of the decline is unknown but is commonly associated with a combination of improper cultivation, old age, and possibly one or more opportunistic pathogens. Improper cultivation, such as too much or too little water, soil compaction, excessive and/or inappropriate pruning, root disturbance or damage, wounds, and competition from adjacent encroaching plants, could stress trees and predispose them to opportunistic pathogens. Because most of the trees exhibiting this decline are old and mature, perhaps overly so, natural senescence is likely a significant contributing factor; rarely are young, small trees, which are usually vigorously growing, showing symptoms. Symptoms generally indicate root damage or death, but isolating soil-borne root pathogens associated with the decline has been difficult and mostly inconclusive. While Phytophthora, Armillaria, Fusicoccum, and Botryodiplodia have been isolated from some declining Victorian box trees, these pathogens are not thought to be the sole or even primary causal agents responsible for the decline. Thus, a combination of factors, including old age, improper cultivation, and several disease pathogens, is likely responsible for the decline.
Provide Proper Cultural Care
The best management strategy for Victorian box decline is prevention through proper culture. When planting a Victorian box, select the right location in the garden or landscape; and plant and care for it properly. Irrigate appropriately, applying sufficient water at each irrigation event to moisten the upper 12 inches of soil. Irrigate again only when the soil one to two inches deep becomes dry, then irrigate once again to moisten the upper 12 inches of soil. This irrigation strategy allows for a slight dry down between irrigation events and encourages a deeper and healthier root system. Avoid disturbing or wounding the roots or compacting the soil; maintain a one- to two-inch layer of mulch (fallen leaves, grass clippings, etc.) over the root zone and six inches from the trunk. Prune only to remove dead branches or to maintain good structure, and when doing so adhere to sound and appropriate pruning practices. Keep encroaching turf grass, groundcovers, shrubs, and weeds at least three feet away from the trunk. Prune back adjacent trees encroaching or overtopping the Victorian box's canopy. Remember that old trees seem more susceptible to the decline, so where practical consider replacing senescing trees with an appropriate species and individual tree.
What about Chemical Control?
There is no proven chemical treatment for declining trees. However, applications of gypsum (calcium sulfate) at the rate of 10 pounds per 100 square feet might help to suppress some root pathogens that may be present.
For information about pests and abiotic disorders on Victorian Box, visit the UC IPM web site.
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