Is it okay to cover the base of a tree with extra soil?

The buttress or basal portion of a tree should never be covered by soil as this practice increases the chance that the tree will suffer from root pathogen attacks in the submerged part of the trunk. The soil should be removed until root flares at the base of the tree are clearly visible. Attacks by […]

I just cut down a small infected bay. Do the root shoots carry P. ramorum?

Bay shoots do not carry P. ramorum because the pathogen is not systemic in bay.  Each leaf is infected independently. Additionally, there is no root infection in most P. ramorum hosts,  particularly California bay laurel.  However, when bays re-sprout, they may be re-infected.  

Are there any treatments available for an oak with Armillaria (oak root fungus)?

Once an oak has the oak root fungus Armillaria (often due to excessive watering),  most treatments will be ineffective. Be sure the base of the tree is free of mulch and other organic debris and slightly expose the root system at the root collar. While fertilizing may not help, try using one bark application of […]

My pear tree was looking great. Within a week one of the limbs died and now it looks like the whole tree is dying.

It sounds like your tree is having problems providing enough water to the canopy to keep the foliage and cambium alive. If you are not watering it, that may be the problem. If you are watering it, your tree may have contracted a root disease. In that case, it is important to clear all organic […]

If the stump of a felled tree is left in place, can the roots to continue to grow?

A lot depends on when the tree is felled. If a tree is cut in winter, it is possible that the root system will experience an additional year of growth. What happens to the root system depends on many variables, including soil type and presence of other trees of the same species adjacent to the […]

Armillaria is slowly killing my Thuja hedge. What is a comparable replacement hedge that will give me the same amount of privacy and be resistant to this fungus?

The first question to ask is what type of irrigation is being used currently on the hedge. Most landscape oak root fungus problems are due to overwatering in summer months. However, Thuja orientalis (=Platycladus orientalis) is quite susceptible to Armillaria even without heavy irrigation as highly susceptible species do not require excessively high soil moisture […]

What is the Critical Root Zone around a tree?

A tree’s Critical Root Zone (CRZ), sometimes also called the Root Protection Zone (RPZ), is defined as a circle on the ground corresponding to the dripline of the tree. Unfortunately the “dripline” of a tree can be irregular and hard to define. An alternative method of determining this dimension is to measure the diameter of […]

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