Common Disease / Pest & Defects

Below is a list of Trees that are common in our area; these species of trees are also susceptible to the listed diseases, pests, and defects.

CalleryPear Tree (Pyrus Calleryana): Fire Blight and Fungi are plaguing pear trees throughout the Bay Area; in fact, it’s so common that if you find a pear tree that doesn’t have at least one of these that would be uncommon.

Symptom of Fire Blight: Black to brown leaves that cling to the stems and don’t fall off, they usually cling in bunches.  There are no known cures for this bacterial disease.  Believed to be spread through mild weather, birds, and/or pruning tools.

Symptoms of Fungi: Blotched leaves, almost like little black-like freckles sprinkled throughout the foliage of the tree. Fungicides can be used to spray the trees before they leaf out in early spring and should be applied a few times.  Customers don’t often find treatment of this fungi (Pacific Coast Pear Rust) because the reinfection rate is high, the cost of treatment is high, and is usually not at all a contributor to death so long as the tree has an abundant amount of foliage to continue producing photosynthesis, the fungi just makes it sort of unsightly.

Canary Island Date Palm (Phoenix Canariensis): Fusarium Wilt Disease is terminal, meaning once infected, the tree will die.

Symptoms: entire fronds die prematurely, usually half of each frond dies. The number one vector for spreading the disease is pruningso make sure your Tree Trimmers sterilize their pruning equipment before they touch your tree as it could cost you tens of thousands of dollars if your tree becomes infected.

Japanese Maple (Acer Palmatum): Unfortunately Japanese Maple trees are prone to cankers, fungi, which spreads throughout the tree until the canker girdles the stem and stops the uptake of water and nutrients at which point there is dieback at the tips up the branches.  There are two types of cankers, perennial and annual. The annual canker grows and spreads at a rate faster than the Japanese maple can heal over it so the tree slowly succumbs to the canker.

Symptom: Sunken lesions are sometimes covered in exfoliating bark, usually several cankers throughout the tree, dieback in top portions of the tree, and branch tips.  It’s a slow death, remove dead branches and when doing so renders the tree unsightly, then remove the tree.

Myoporum Tree: Anyone who has one of these trees would notice the leaves are curling and have stunted growth.  This is due to a pest called Thrip (Thysanoptera), which is hard to see with the naked eye. These pests are widespread in the Bay Area and are a nuisance. Thrip prevents the development of leaves and causes premature leaf drop, all of which prevents photosynthesis leading to the decline of the tree. Avid, Merit 21 and Sevin are pesticides that have been used to treat Thrip. It is recommended to consult with licensed pesticide personnel to treat your trees.

Weed Abatement

Queen Palm Tree: Unlike most of the other common palm trees, the Queen Palm is sensitive to nutrient deficiencies, specifically manganese.  Nutrient deficiencies can lead to serious deformations such as Frizzle Top, Inverted Cone, and others. To prevent this, any local nursery should have palm tree-specific fertilizer, please follow directions. Whole palm tree failure is rare; however, inverted cone, depending on the severity can render the tree unstable and a hazard.   (Note to Tom:I’d like the Pict titled “frizzle top” and “inverted cone” in the “common disease/pests & defects” folder next to this queen palm paragraph.)
Co Dominant Stems and included bark.

Leaning Tree: There are endless amounts of culprits for a leaning tree.  The pine trees in Monterey California are said to be sculptured by the wind, and yes, you will find that they’re leaning in the direction of the prevailing wind, a beautiful sight.  However, the number one reason trees develop a lean in our neck of the woods is due to competition for light, usually influenced by competing trees or structures, much like the plant in your kitchen that grows towards the window.  Plants release hormones into foliage that receive the most light and promotes growth in this foliage. This phenomenon is referred to as phototropism. Just like anything else, you’ll find an endless amount of opinions on how to create this.