The official blog of the Oregon State University Plant Clinic
Now is the time when nurseries are propagating plants for the upcoming spring season. Odd looking plants with too many shoots or buds could be infected with the pathogenic bacterium Rhodococcus fascians. Propagators should be alert for symptoms, as shown in the gallery below, and have suspicious plants tested for the presence of the bacteria.
Boxwood blight is a relatively recent disease that is devastating Buxus plants on the east coast, and which has made limited inroads in Oregon.
The cannabis aphid is a pest aphid found on the leaves and stems of cannabis. Aphids have "piercing-sucking" mouthparts to feed on plant fluids. When aphids occur in high numbers, their feeding can stress plants and cause wilting, yellowing and other damage. Cannabis aphids are also potential vectors of plant pathogens.
Jerusalem crickets seem to fascinate those who find them. Also known as potato bugs, devil’s babies, and niña de la tierra (child of the earth), they are members of the genus Stenopelmatus and are related to katydids and cave-dwelling camel crickets.
Plants require soils that allow their roots to exchange oxygen with the soil, soils in which their roots can expand and grow, and that have adequate moisture retention capability. Trees surrounded by paving have limitations to all these necessary conditions.
The Asian gypsy moth (AGM) is an exotic pest that is considered a potentially serious threat to North American forests. It is a close relative of the European gypsy moth, which is well-known for causing widespread damage in eastern US forests.
The weather this fall has been ideal for development of molds (like Botrytis) in the tight colas of the hemp plant. The alternating cool and moist weather followed by a few clear days of moderate temperatures have been perfect for the moisture-loving fungus. Which translates to bad news for the growers, who depend on the flowers for their CBD-related products.
The practice of making a planting hole with an auger and stuffing in a young plant can cause problems as the plant grows. Although handy [...]
Squirrels go after more than acorns on oaks, sometimes to the point where people become alarmed that the trees are diseased.
The Japanese beetle (Popillia japonica) is an exotic invasive beetle that is considered a serious plant pest in the United States.
Plants that appear to be doing well in the spring, but then crash in the heat of summer could be missing something – literally. We have received a number of different woody plants showing poor vigor, reduced growth, sun scald on the leaves or stems, small leaves, and branch dieback, all leading to a slow decline of the entire plant and eventual death.
If you’re curious about who might have left that silvery slime trail along your walkway, or who might be munching on your garden plants, we have a handful of online resources to help you identify and learn more about the slugs and snails of Oregon.
Fungal diseases are often associated with intermittent rains and mild weather and the long hot days of late summer don’t seem ideal for fungal growth, but they are perfect for the powdery mildews.
Cooler nights and days of fall can create conditions that encourage the disease known as downy mildew. This problem is caused by an organism that is more closely related to brown algae than to fungi: Hyaloperonospora parasitica.
The box tree moth is a potentially serious pest of ornamental boxwood. The caterpillars cause widespread damage by feeding on the leaves and defoliating or killing host plants.
The Asian longhorned beetle (ALB) is an exotic invasive wood boring beetle that infests and kills healthy trees, including ash, birch, elm, maple, poplar and willow.
The spotted lanternfly is an exotic invasive planthopper insect that feeds on a wide range of fruit, ornamental, and hardwood trees. Its establishment and spread poses a serious threat to US agriculture.
The emerald ash borer (EAB) is an exotic invasive wood-boring beetle that infests and kills ash trees in its introduced range. EAB presents a significant threat to ash trees throughout North America.
Hobo spiders (Eratigena agrestis) are not native to North America and were accidentally introduced here from Europe. These spiders are long-legged, swift-running spiders that build funnel or tube-shaped retreats. Like most spiders in this family, hobo spiders are most active at night.
The ponderous borer is probably the largest beetle that occurs in Oregon. Even though it is so spectacularly large that it looks like it should come from a tropical rainforest, it is actually native here.