Common Cultural: Air pollution categories: Common Problems Cultural Problems revision date: 2022-11-01 11:39 Air pollution damage on dahliaPhoto by: R.S. Byther Biology Generally, air pollution damage in the Pacific Northwest has been considered limited. Sulfur dioxide damage from large industrial emissions has been known to cause interveinal bleaching on dahlia, interveinal spotting on lilac, and […]
Common Cultural: Chlorosis categories: Common Problems Cultural Problems revision date: 2022-11-01 11:35 Chlorosis on Japanese spurge caused by excessive sunlightPhoto by: R. Maleike Biology Chlorosis is the fading of the green color in plant leaves. It can be caused by environmental stress, nutrient deficiency, chemical deficiency or injury, disease, and the feeding of insects or […]
Common Cultural: Construction damage categories: Common Problems Cultural Problems revision date: 2022-11-01 11:30 Tree root damage and dieback from constructionPhoto by: R.S. Byther Biology Disturbances in the root zone such as cutting roots, covering roots with sidewalks or pavement, adding a layer of topsoil, changing soil grade, or changing water drainage patterns can damage or […]
Common Cultural: Desiccating wind categories: Common Problems Cultural Problems revision date: 2022-11-01 11:26 Winter desiccation on rhododendron leavesPhoto by: R. Maleike Biology Dry, cold wind, usually from the north, results in desiccation (dehydration) of plant tissues. During periods when the soil is frozen, water movement slows or stops in plant tissue, enabling wind to dehydrate […]
Common Cultural: Drought damage categories: Common Problems Cultural Problems revision date: 2022-11-01 09:46 Dead upper branches on conifer from drought damage Photo by: R.S. Byther Biology Marginal and tip leaf necrosis may result when insufficient moisture is available to broadleaf plants. The terminal growth and sometimes side branches on conifers may die because of excessive […]
Common Cultural: Fasciation categories: Common Problems Cultural Problems revision date: 2022-11-01 09:42 Fasciation showing a flattened, twisted, ribbed stemPhoto by: R.S. Byther Biology Fasciation occurs in many kinds of plants, both woody and nonwoody. Stem growth becomes flattened and often takes on a dramatic twisting due to changes in the genetics of the growing point […]
Common Cultural: Fertilizer burn categories: Common Problems Cultural Problems revision date: 2022-11-01 09:37 Marginal leaf necrosisPhoto by: R.S. Byther Biology Excessive use of fertilizers can damage or kill plants. High levels of salts in the soil will damage plant roots, resulting in reduced water uptake. The salts may also accumulate in leaf tissues, causing a […]
Common Cultural: Frost injury categories: Common Problems Cultural Problems revision date: 2022-11-01 09:34 Flower bud damage on rhododendronPhoto by: R.S. Byther Biology Frost can damage new growth and flowers in the spring. Severity and distribution will depend on stage of plant development and where plants are growing; low-lying areas often act as frost pockets. Symptoms […]
Common Cultural: Hail damage categories: Common Problems Cultural Problems revision date: 2023-01-09 12:00 Tattered leaves and pear fruit damaged by severe hailstormPhoto by: M. Bush Biology Hail damage can vary from minor leaf spots and shredding to complete defoliation. Scarring of fruit may also occur. Minor damage may not be immediately apparent. Distribution of damaged […]
Common Cultural: Lime-induced chlorosis categories: Common Problems Cultural Problems revision date: 2022-11-01 09:23 Lime-induced chlorosis on rhododendronPhoto by: R.S. Byther Biology Lime-induced chlorosis is a yellowing of leaves caused by alkaline soil conditions. High alkalinity (high pH) of soils can make iron or manganese less available to plants, resulting in symptoms of nutrient deficiency in […]
Common Cultural: Marginal leaf necrosis categories: Common Problems Cultural Problems revision date: 2022-11-01 09:21 Marginal leaf necrosisPhoto by: R.S. Byther Biology Marginal leaf necrosis can be caused by numerous factors that restrict the flow of water to the leaves, such as drought, salt damage (fertilization), root rot, cankers, excessive heat, and chemical injury. Symptoms include […]
Common Cultural: Morphological changes categories: Common Problems Cultural Problems revision date: 2022-11-01 09:17 Biology
Common Cultural: Mosses and lichens categories: Common Problems Cultural Problems revision date: 2022-10-31 02:56 Lichen on rhododendron branches closeupPhoto by: C.R. Foss Biology Mosses and lichens are primitive plants often found growing on the bark of older trees and shrubs. They are typically grayish, greenish, or orange in color and may be flat or branched. […]
Common Cultural: Needle loss categories: Common Problems Cultural Problems revision date: 2022-10-31 02:48 Pine natural needle dropPhoto by: R. Maleike Biology Conifer trees periodically shed older needles. In the early fall following a dry summer, western red cedar often dramatically shed older needles; this is known as cedar flagging. Broadleaf evergreen plants also show periodic […]
Common Cultural: Needle tip necrosis categories: Common Problems Cultural Problems revision date: 2022-10-31 02:43 Needle tip necrosis on sprucePhoto by: R.S. Byther Biology Needle tip necrosis can be caused by numerous factors that restrict the flow of water to the leaves, such as drought, salt damage (fertilization), root rot, cankers, excessive heat, and chemical injury. […]
Common Cultural: Nutrient deficiency categories: Common Problems Cultural Problems revision date: 2022-10-31 02:40 Interveinal chlorosis symptoms of iron deficiencyPhoto by: R. Maleike Biology An insufficient supply of mineral nutrients can result in a variety of symptoms on plants. Nitrogen deficiency typically causes a chlorotic yellowing of older leaves. Iron deficiency symptoms are observed on the […]
Common Cultural: Oedema categories: Common Problems Cultural Problems revision date: 2022-10-31 02:07 Watery blisters on hosta leaf from oedemaPhoto by: R.S. Byther Biology Oedema usually appears first on the lower leaf surface as watery blisters. As they age they become brown, yellow, or rust-colored and may resemble disease symptoms. It is very common on geranium […]
Common Cultural: Overwatering or poor drainage categories: Common Problems Cultural Problems revision date: 2022-10-31 01:58 Standing water at base of tree from overwateringPhoto by: R. Maleike Biology Overwatering or poor drainage (wet soil) can cause the death of plant tissue from the ends of branches to the entire plant. Symptoms often initially appear as wilting, […]
Common Cultural: Plant girdling and circling roots categories: Common Problems Cultural Problems revision date: 2022-10-31 01:53 Complete dieback caused by girdling at the crownPhoto by: R.S. Byther Biology Girdling interrupts the flow of manufactured food, hormones, and other metabolites from the leaves to the roots. The roots may eventually starve, and then the top branches […]
Common Cultural: Poor pollination categories: Common Problems Cultural Problems revision date: 2022-10-31 10:50 Poor pollination on cherryPhoto by: R.S. Byther Biology Fruit may fail to develop properly or may drop prematurely if pollination is poor. Several factors may cause poor pollination. Some fruit trees require a tree of a different variety for viable pollen. Cold […]