The dry winter and spring in the west have brought us to another year where drought stress potentially becomes our most prevailing discussion and priority during the upcoming summer and fall. The lack of winter rain and quickly melting snow pack has already impacted the health of trees throughout our region and beyond. Combined with the prior year drought issues over the past seven to ten years, we anticipate not only will trees struggle much more this year and will take much longer to recover than normal.
How can you tell if your trees have pests or diseases? These problems can be challenging to recognize due to the sheer number of possible issues, and the fact that they may occur far above your head where they are difficult to spot! For this reason, pest infestation and tree diseases often go overlooked for years, then appear to progress quickly because they have gone unnoticed. Fortunately, there are common signs of poor tree health that can help you identify these problems early so you can get help from a professional arborist before you lose valuable trees. Find out if your trees have pests or health problems now with this handy list.
The Asian citrus psyllid is garnering a lot of attention lately, largely because it spreads a serious disease called citrus greening disease or huanglonbing.
The insect itself is a fairly important pest on citrus. It is native to Southwest Asia and introduced to the United States in 1998 and in California in 2008. They are smaller, brownish insects that are fairly hard to spot until they begin to do damage. The adults lay eggs on citrus leaves and when the young hatch they feed on the leaves, exuding a sticky substance called honeydew. This sticky mess on a citrus plant is often the first noticeable problem. Leaves will turn a pale green, with twig dieback and lead to small, underdeveloped fruit if not controlled.
The benefits of enlisting the help of an arborist in parks and forests are clear. However, in urban environments, you may overlook the advantages of partnering with a skilled arborist. Yet, in this environment, an arborist’s role can be even more crucial – benefitting the trees and city residents. What does a city arborist do?
Phytophthora root rot is caused by a soil-borne organism. When first infected, the coast redwood’s foliage may wilt, yellow and dry out but remain on the tree. The leaf damage is because of the slow death of the redwood’s roots, which limit its ability to absorb adequate amounts of water. Eventually, the entire tree will turn brown and is unlikely to recover. If caught early enough, phytophthora root rot’s presence in the soil may be managed, or at least reduced, with the application of a fungicide containing potassium phosphate. But this is not always successful.
One measurement we use in helping to determine overall soil health is soil pH. This is a common concept and important to understand, but is only one of many measurements we use to determine overall soil health. A good soil health recommendation will take many factors into consideration, but soil pH is the starting point, as it helps us determine nutrient availability, the tightness of soils, and the ability of soil biology to thrive or not. The wrong pH may encourage fungal pathogens, while the proper soil pH range will encourage good soil microbes.
The pH scale runs from 0 to 14. Any pH reading below 7 is acidic and any pH above 7 is alkaline. A pH of 7 indicates a neutral soil. Most trees will grow in soils having a pH between 6.5 (slightly acid) and 7.2 (slightly alkaline). Ideally, maintaining a soil close to 6.8 is perfect for most trees. There are a few plants that prefer a soil pH below 6.0. These “acid-loving” plants include azaleas, rhododendrons, and blueberries. The soil pH for these plants can be lowered by incorporating elemental sulfur (S) into the soil. Since the soil acidifying response to elemental sulfur is slow, it should be applied and incorporated a year before planting.
Recurring periods of drought seem to have become commonplace in the Western US in recent years. The effects on trees and shrubs can often be seen in both natural and man-made landscapes during the severest of droughts as leaves wilt, show marginal scorch, or prematurely drop from the plant. However, the long-term effects of drought on the health and survivability of woody plants are less obvious.
Keeping a watchful eye on tree wellness is crucial to preventing damage from common tree diseases in the Seattle area. What symptoms should you be on the lookout for in your Seattle, Bellevue, Kirkland, Redmond, Kent, Edmonds, or Bothell property’s trees?
