Jerry White

Arbor-wellness: Needle Blight

My spruce trees are starting to turn brown, can you help them? 

It does depend on what is wrong with them, but many of our evergreen trees easily develop one of many fungal diseases that kill either the needles, the tips of a twig, or entire branches. Newly developed needles that die can affect the overall health of the tree, so understanding what the problem is and how to prevent it can be important. 

How bad will the damage be?  

It depends on the type of disease. Some are minor problems, some will eventually kill the tree. But seeing this problem may indicate your trees are already stressed in some other way. Asking one of our certified arborists to review the problem and recommend a course of action is a wise thing to do. 

What can I do about it?  

There are treatments that work on most types of needle or tip blights. They are especially helpful when the tree is not severely affected yet. Old needles can’t be helped but we can discourage spreading these problems to new needles with timely treatments. 

Knowing what kind of disease, how bad the problem is, and what the best course of action would be is something we at Arborwell can do for you. 

If you are concerned about any diseases on your spruce or evergreen trees and want to schedule an inspection, click the button at the top of the page!

Arbor-wellness: South American Palm Weevil

Why do so many palms look like they are dying? It seems like the top fell off and only the side leaves are left.

This is a sign of a new pest species invading the southern California region called the South American palm weevil. It is a large, black insect that deposits eggs in the top of the palm tree. The larva eats through the main upper part of the palm tree, eventually killing it. 

Will it affect all palm trees?

The primary palm it invades is the Canary Island date palm. However, other palms, including our native California fan palm tree, are possible targets as well. We are carefully monitoring this situation with all palms just to be prepared.  

Will it spread to other areas?

This large insect is a long distance flyer. Studies indicate it can fly as far as 15 miles in one flight. It was only present in southern parts of San Diego region a few years ago but has spread further north and east as it expands its range in the US. It has also started to become a problem in other southern states with Canary Island date palm populations. 

I see black round plastic boxes by some palms, what are those?

White or black weevil traps are being set in areas to help determine the spread of the insect to new areas. This helps determine how quickly it is spreading into new areas. 

Can you do anything about it?

There are controls for this insect, but they are only effective when preventing an attack or very soon after that. We know that if your palms are healthy, watered correctly and not otherwise having problems, the current control measures will be more effective. Because this seems to be a serious pest problem, avoid planting new Canary Island date palms in the future.  

When should I remove an affected palm tree?

If you suspect your palm might have this insect, contact your Arborwell arborist right away. We can determine if your palm has this insect and safely remove and dispose of those that are affected.  Remember they kill a palm quickly, so being proactive with protection of prized trees is important for their survival.

If you are concerned about the South American palm weevil and want to schedule an inspection, fill out the form below.

Arbor-wellness: Invasive Shot Hole Borer

If you have paid attention at all to the news the past few years, a very small beetle has made big news in Southern California. And rightly so, because it is one of the most destructive invasive pests we have encountered. Polyphagus shot hole borer is a very small beetle that attacks over 600 species of trees and shrubs in our region. It is currently found in L.A., Orange, San Bernardino, Riverside & San Diego counties. There is a very close relative of this beetle, called the Kuroshio beetle. They look exactly the same (even to entomologists) and cause very similar damage. Now the scientists are calling BOTH of them “Invasive shot hole borer”, which we have started doing as well. 

They are also called “ambrosia” beetles, which refer to beetles that carry a symbiotic fungus with them that is transferred to new trees when they burrow into a tree. It is this fungus – a type of fusarium wilt – that typically kills the tree.

What makes the understanding and control of this beetle even harder is that while it attacks a large number of trees and shrubs, it typically only reproduces in about 60 species, mostly hardwood trees. These include alders, avocado, box elder, liquidambers, maples, oaks, sycamores, and willows.

What can we do about it? Every site is different, so we really love to visit a site, see the trees currently there and discuss your budget and goals for the site. There are ways to protect trees if they haven’t been attacked, or to stop the problems if the tree is not too severely infected. Strategic removal of trees that are not a high priority for the site can be discussed as well.

If you are concerned about invasive shot hole borers and want to schedule an inspection, fill out the form below.

Arbor-wellness: Spider Mites

Will they harm humans or animals? Spider mites specifically only feed on plants, thus they cannot harm animals or humans. 

Where do they come from? They are dormant on the bark or other parts of the tree in winter, and re-emerge in the spring or summer. They are tiny and can be carried by the wind, or even when animals brush up against an affected tree or plant and move them on their fur. 

How do they damage my trees? They remove chlorophyll from the leaves and slow plant vigor and health. In severe cases, they can actually kill a plant, but that is rare. 

What can I do about it? There are many species of spider mites, but their control is similar. The most important distinction between types is determining if you have warm season mites or cool season mites. This determines the timing of some of the treatments. There are a variety of ways to control mites, including ways to reduce populations naturally.  

  • Proper pruning can help. This reduces the conditions in the tree that favors mites.  
  • Canopy washes help by simply wash off dust and mites. If the population is not high, this can be effective control in itself.   
  • Systemic treatments prevent populations from establishing. These are best to apply before the growing season.  
  • Canopy treatments geared specifically to spider mites are options when the population builds enough that they are damaging plant health.

If you are concerned about spider mites and want to schedule an inspection, fill out the form below.

Arbor-wellness: Oakworm

There are a lot of caterpillars on my oak tree, will they kill my tree?

They usually don’t kill your oak tree outright, but they can weaken the tree and make is easier for other problems to develop.

What should I do if caterpillar pests are eating my oak tree leaves?

The first step is to identify the problem correctly. We can help with that.

The next step is to decide on a course of action. Depending on the needs of the tree and how bad the infestation is, you have several choices.


What are the most important steps? 

Help your trees get healthy. Our oak trees are still recovering from the long term drought we experienced. Proper watering and nutritional needs are important. Oaks can be damaged by too much water, but not enough is a problem too. While they are adapted to long dry summers, the lack of rain in the winter for 5 years weakened the root systems of these trees. We may recommend deep, infrequent watering to help your trees recover. This is one of the most important things we can do.

Fix soil problems. Poor or compacted soil conditions, reduced rooting area and other soil issues all contribute to tree decline. Improving soil structure, de-compacting the soil, improving soil biology all help the tree get healthy again.

Protect your oaks for other invaders. There are many other insects and diseases that can attack your oak trees, especially if they are stressed from oakworm attacks. After we assess the trees, we may recommend proactive treatments to help protect your oaks while they recover.

Be proactive about caterpillars. If this is a reoccurring problem, the best time to treat is BEFORE the insects hatch. We can protect the trees with treatments made in the fall or winter that will reduce the population the following growing season. This is a very cost effective and safe treatment that stays inside the tree, so only insects that feed on the leaves are affected.

Treat today’s problem carefully. If there is a large population that is severely hurting your oak trees, we may recommend a canopy treatment with a biological control to slow down the problem fairly quickly.

If you are concerned about oakworm and want to schedule an inspection, fill out the form below.

Arbor-wellness: Anthracnose

Why are the leaves falling off my trees when they just leafed out? If you have sycamore trees, dogwood, Modesto ash or certain oak trees, they may be suffering from Anthracnose. This is a leaf disease affecting these tree types and a few others. The leaves are infected when they first come out, but the disease spreads and gets worse as the leaves mature. About the time your tree should be producing shade and capturing sunlight for energy production, the leaves die and drop off, creating a mess on the ground. On some trees, like the sycamore, the disease can affect the small twigs as well. Thus, you often see small and medium sizes twigs falling off these trees throughout the summer.  

Will this kill my tree? While anthracnose in and of itself does not kill a tree, it weakens the tree which allows other insects or diseases to attack the tree more readily. This happens because fewer leaves on the tree means it is not producing enough energy to make the auxins and other chemicals needed for tree defense. The tree also has to expend extra energy to put out new leaves, which often come later in the spring or in early summer.  

Why do my trees have this problem? Anthracnose likes cool moist weather, so a prolonged cool spring, with rain, fog or other moisture encourages the development of the disease. One good thing about this disease is that it is typically host specific, meaning that the anthracnose on your sycamore will not infect your maple trees. 

What can I do about it? The best way to discourage anthracnose is to make sure your trees are healthy and are pruned properly. Water properly – deep, infrequent watering throughout dry times, encourage proper growth with good nutrition and soil health (we usually recommend an organic based feeding that does both of these things), mulching to reduce water loss and tree stress. If your trees can benefit from treatment, it is best to start in the fall or early spring before the leaves come out. Sometimes multiple treatments are best, depending on the weather and the type of tree. 

If you are concerned about anthracnose and want to schedule an inspection, fill out the form below.

Arbor-wellness: Powdery Mildew

Why are the leaves on my tree looking whitish? 

During the spring, especially when it is cool and damp, your tree may be affected by powdery mildew. This is a fungus that punctures the leaves of trees to feed on the cells of the leaf. The fungus then grows on the surface of the leaf, making a white powdery look to the leaf surface. 

Will this hurt the tree? 

Most of the time, powdery mildew does little long-term damage to the tree. It often goes away on its own as the weather dries and warms. However, it indicates that there may be some other problems with your trees. Healthier trees that have been pruned properly often have much less powdery mildew. Trees planted in too much shade tend to be affected the most, so creating more sunlight in an area may reduce the problem. In a few cases, it can become so bad that the tree fails to thrive and needs to be removed. 

Will all my trees get this problem? 

No, many trees are very resistant to powdery mildew. Some trees that are more susceptible include apple, crabapple, crape myrtles, dogwood, flowering fruit trees, hawthorn, lilac, maple, oak, poplar and sycamore. 

When is the best time to protect these trees? 

Improving the health of the tree or pruning can occur as needed. When treatment is recommended, doing a preventative treatment in the fall or early spring is best. Control during the season is possible, but often requires several return visits to maintain good control. 

If you are concerned about powdery mildew and want to schedule an inspection, fill out the form below.

tree care services

Arbor-wellness: Bronze Birch Borer

One of the most beautiful trees in the landscape is the birch tree. Soft foliage that flutters in the wind, smooth white or papery cream bark and beautiful fall colors make this tree a favorite for many people.

Unfortunately, it is also the favorite tree of a destructive insect called the bronze birch borer. This relatively small flying beetle has a deadly appetite for birch trees, burying through the outer bark to lay eggs inside the tree. The new larvae then eat the living tissue right below the bark, stopping the water and nutrients from getting to the top of the tree.

Dead tops on birch trees are the first visible sign, but protection of your trees should begin before then.

Your Arborwell arborist knows how to create a sound, cost effective plan to protect these trees in your landscape.

If you are concerned about the bronze birch borer and want to schedule an inspection, click the button at the top of the page.

How can we help you? Lets Talk