If you have been the steward of plants and trees for a few seasons, you will recognize that some species at certain times of the year start to develop issues in the leaves or become infested with insects. Each season we assist tree and plant owners with managing and treating these issues when they arise and our hope this year is that we can provide you with the tools needed to proactively manage these issues so that they do not impact the health or appearance of your vegetation. This newsletter will provide a step by step process to get ahead of these diseases and hopefully ensure you don’t have to deal with sap dripping on your car from the overhead tree limbs, your peach tree losing all of its leaves this summer, or your roses becoming infested with aphids. The reason we chose to provide this tip in February is because it is the best time to start being proactive with your treatments. Treating deciduous trees before the leaves emerge is the best time to prevent leaf fungal issues and insect infestations.
A Step By Step Process To Proactive Treatment
Every tree or plant has certain pests, or diseases that it is prone to. They are also more common in certain parts of the country than others. We will be focusing on the plants within the bay area region.
1. Identification
First Identify the tree or plant. Crape Myrtle, Plumb, Japanese maple, etc..
Use these links to help identify your tree:
https://urbantreekey.calpoly.edu/
https://www.arborday.org/trees/whattree/
https://calscape.org/loc-California/cat-Trees
2. Weaknesses
Once you identify the exact tree or plant you have, then understand its weaknesses. Every plant has its kryptonite and if you know what they are you can protect them from being exposed to them. You can find the weaknesses by looking the tree up in the database to understand the pests and diseases it is prone to.
This is a simple guide to understand the main issues: https://selectree.calpoly.edu/
This is more advanced to discuss treatment options and provides more details of damage caused by these pests or diseases: https://ipm.ucanr.edu/PMG/menu.homegarden.html
https://ipm.ucanr.edu/home-and-landscape/plant-problem-diagnostic-tool/
3. Lifecycle
When you find out the pest or disease you need to treat for, then you can be proactive in preventing an outbreak or infestation. Performing this task requires some knowledge of the insect or disease lifecycle. Some insects or diseases are only active at certain times of the year, and if you can time your application early you can target the pest before it ever damages the plant. On the University of California’s pest management website you can find details on the lifecycle for each pest or disease.
For Example: Anthracnose begins to be active in the spring on the leaves of Sycamore and ash. Knowing this I would start treatments during the dormant season before the leaves emerge because once the leaves come out it may be too late.
https://ipm.ucanr.edu/PMG/PESTNOTES/pn7420.html
4. Treatment
Once you understand the pests or diseases your plant is prone to then you can look at treatment options. There are various methods of treating and each has its benefits but depends on the particular issue treated, and the surrounding environment.
Here are the most common treatment methods:
Cultural Control: This is one of the most important components. Make sure the tree or plant is in an environment that it thrives in. Oftentimes a plant will develop issues when it is stressed or in growing in the wrong environmental conditions. If that is the case it may require some adjustment of the site.
Example: Trying to treat roses for leaf fungus when they are located in the shade and being irrigated by overhead sprinklers. The first step should be to improve the environmental condition that roses can thrive in. Allow more sunlight into the area and change irrigation to drip instead of sprays.
Biological Control: This is the process of using natural enemies or predators to fight pests. This is more commonly used when treating pests rather than fungi. Some common examples of this are implementing lady bugs into the garden to battle aphids, parasitic wasps to battle scales, or BT to treat oak caterpillars. This biological approach provides the least impact to the environment and often develops a more balanced ecosystem.
Chemical control: We try to reserve this as the last resort when treatment but can also be a good option when trying to be proactive. Now that we are confident whether we are treating an insect or fungus we can determine what chemicals can be used to spray the tree or plant to treat or prevent an infestation. There are multiple options when it comes to chemicals.
- Organic: These would include horticultural oils, dormant spray oils, neem oil, orange oil, and other oils derived from plant parts. These are great options to use. Because they require more applications it can be more costly to perform these on larger trees or shrubs. When treating edible plants this is always the best way to treat.
- Conventional: This would be using some chemicals available from the hardware stores for the home gardener or restricted chemicals only available to licensed professionals. We find these are helpful in situations where the other options are not working or offer little control.
Example: When treating bark beetles we can apply a systemic insecticide to protect the trees from the inside. This is only used on non edible species. This offers a control that organic methods would do very little to help with.
Identifying pests and diseases and determining the best treatment method can sometimes be challenging. The resources provided will provide great assistance when trying to do this on your own. As arborists we are trained and educated on the identification of these issues and developing plans to treat them with the least impact to the environment. As we strive to care for trees and help them thrive within the bay area, developing proactive treatment plans for various properties helps us keep plants thriving and healthy. If you find you need our help with developing a plan or diagnosing issues we are always available to meet with you and diagnose each plant.
Most Common Issues We Treat
One last item we want to provide is some tips to treat some of the more common issues we expect to receive inquiries about this coming summer and spring. We will provide an example of the issues and treatments we most commonly treat.
Peach Tree leaf curl:
https://ipm.ucanr.edu/PMG/PESTNOTES/pn7426.html/
Chinese hackberry aphids:
https://ipm.ucanr.edu/PMG/GARDEN/PLANTS/INVERT/hackaph.html#:~:text=On%20large%20trees%2C%20the%20most,into%20hackberry%20trunks%20or%20roots
Oak tree caterpillars:
https://ipm.ucanr.edu/PMG/PESTNOTES/pn7422.html?src=AR16
Zylosma White flies:
https://ipm.ucanr.edu/pmg/pestnotes/pn7400.html
Crape Myrtle Powdery Mildew:
https://ipm.ucanr.edu/PMG/PESTNOTES/pn7493.html
Roses with rust: