Summer is here, and so is the Stanislaus County Fair! Our brand-new University of California Cooperative Extension (UCCE) Master Gardener Program is excited to have a presence at the fair this year, with volunteers who have just graduated this past June.

Pick up free copies of Quick Tips cards on pests like ants, powdery mildew, cockroaches, and more! We'll also be giving away carrot and California poppy seeds (while supplies last).

Want to be a UCCE Master Gardener in Stanislaus County? We have flyers with all the information you need and will be taking applications next week!

For more information about the fair, visit the Stanislaus County Fair website. 

Although many coast redwoods (Sequoia sempervirons) appear to grow well in some parts of the San Joaquin Valley, the UCCE Master Gardeners are often contacted for help diagnosing redwoods with dead branches that seem to be dying.  

It's important to remember that coast redwoods are native to the coasts of Central and Northern California. In this environment, the trees are shaded by each other and experience significant cooling from fog. They also receive moisture from fog drip and high rainfall. In their native forests, redwoods grow with large amounts of forest litter over their roots. 

Dead redwood trees. (Ed Perry, UCCE Stanislaus)

While coast redwood trees are susceptible to some serious diseases, they are most often injured or killed by abiotic (non living) problems. High soil salinity caused by excess sodium (alkaline soil), and toxicity caused by high concentrations of specific ions such as boron and chlorides will stunt their growth and cause their leaves to turn yellow and “burn.”  They grow poorly in heavy soils that are too wet, or in dry, compacted soils with poor drainage. Coast redwoods are also susceptible to iron deficiency, especially in high pH soils. They may be injured by freezing temperatures, especially in dry soil. Because they are adapted to a cool, moist environment, they will develop brown and scorched leaves during our hot and dry summers, especially if they're not adequately watered. Drought stressed trees may then be attacked by bark beetles.

In dry or compacted soils the trees grow slowly and their trunks develop a distinct taper. Under ideal soil and moisture conditions, such as along portions of the California Coast, the trunks will be nearly the same diameter from the base of the tree to several feet high. Some brown foliage in the interior of the tree is normal. In fact, it is normal for the oldest leaves to turn yellow, then brown, and finally drop from the tree in late summer and early fall. It is also normal for short twigs to turn brown and fall. New growth at the ends of branches indicates that the branches are alive and healthy, despite some dieback of twigs and leaves.

Healthy redwood trees. (Ed Perry, UCCE Stanislaus)

As mentioned, coast redwoods are susceptible to some diseases. In Stanislaus County, redwoods infected by Botryosphaeria canker (Botryosphaeria dothidea), crown rot (Phytophthora sp.) and Armellaria root rot (Armillaria mellea) have been identified. However, these diseases are relatively uncommon on redwoods here. If you're trying to diagnose a redwood problem, be sure to consider soil and water-related problems first.

Redwoods are forest trees. We have cultivated them for use in non-forest landscapes as street and park trees, and as specimen trees. These conditions are not always favorable to their growth or long term establishment. They grow best with shade, cool root systems, abundant mulch, and continual moisture that is relatively salt free. If you can create some of these conditions in the landscape, redwood culture and disease management will be much less problematic.

Ed Perry is the emeritus Environmental Horticultural Advisor for University of California Cooperative Extension (UCCE) in Stanislaus County where he worked for over 30 years.

Many gardeners are interested in knowing how winter temperatures affect garden pests. The hope is that following a cold winter–such as this year–fewer pests will survive to plague the garden. Unfortunately, both insect pests and plant diseases have ways of surviving our harshest winters. However, there are some things that you can do to lessen potential pest problems, mostly by eliminating the places where pests and disease may overwinter.

Although a few pests can migrate great distances, many come from sources within your garden or nearby areas, surviving on weeds, in crop debris, as pupae in soil, or as seeds, spores or eggs. You can also unknowingly bring some pests into your garden on infested transplants or contaminated soil or equipment. 

Codling moth larvae inside a fruit. [Credit: Jack Kelly Clark, UC IPM]

Good common-sense sanitation practices will help to eliminate overwintering garden pests. In your fruit trees, be sure to remove and destroy old fruit “mummies” hanging in trees and pick up and destroy any fallen nuts. Old fruits and nuts often contain pests such as codling moths. It's also very important to get rid of pruned branches, especially those from your fruit trees, that might be infested with disease or borers. Bark beetles may emerge from infested branches in late winter or early spring, so be sure to dispose of prunings as soon as possible. Don't forget to treat your fruit trees, especially peach and nectarine trees, with fungicide sprays to prevent spring diseases such as peach leaf curl; oil sprays applied now will also help to control overwintering insect and mite pests on deciduous trees.

Also, remove any weeds around your garden well before planting any new crops. Not only do weeds produce seeds that may find their way into your garden, but they are also likely to harbor numerous migrating pests. For instance, cutworms, earwigs, stink bugs, thrips and certain viruses carried by aphids and leafhoppers are all pests associated with weedy areas. If you wait until your garden is planted before destroying these weeds, the pests will move into your crops. Waiting for the weeds to dry out naturally will also encourage pest migrations. Besides, it's easier to control weeds when they're seedlings, rather than waiting until they've matured and set seeds.

Fruit mummies may harbor pests. [Credit: Jack Kelly Clark, UC IPM)

Good sanitation also means making sure the planting stock you're using is free of pests. Check transplants or other greenhouse stock for aphids, diseases, nematodes and other pests. Use certified seed or stock if available. Make sure any organic soil amendments you use are free of weed seeds and pathogens, and don't move soil infested with nematodes, Bermudagrass stems, or nutsedge tubers to other parts of your garden. If you're not sure whether the soil is infested with pests, it's best to not take the chance. Also, clean equipment before moving it from infested areas.

Always be sure plant debris, particularly residue from previous vegetable crops, is completely decayed or removed before planting a new crop. A good way to destroy most crop and weed residues around your garden is by composting.  Composting destroys most of the pests that may be harbored in the residues.

You can download a free copy of Composting is Good for Your Garden and the Environment to learn more.

Ed Perry is the emeritus Environmental Horticultural Advisor for University of California Cooperative Extension (UCCE) in Stanislaus County.

Who are the UCCE Master Gardeners?
UCCE Master Gardeners are residents in the community trained by University advisors and experts using science-based information. They take a weekly class for 6 months and learn about a variety of topics, including soils, horticulture, vegetable gardening, composting, fruit trees, and many more! After passing an exam, the trainees become certified UC Master Gardeners, ready to answer your questions about home gardening.

You may see the UCCE Master Gardeners at events such as farmer's markets, the library, the fair, or a school garden. They will also be at the UCCE office each week, available to answer your questions.

UCCE Master Gardener Focus

The UCCE Master Gardener Program plans to address local issues related to reducing green waste, conserving water, integrated pest management (IPM), and sustainable landscaping.

The first group of trainees will start their classes in January and finish in June, ready to volunteer. In the meantime, you can still bring your pest or gardening questions to the UCCE office at the Agricultural Center at 3800 Cornucopia Way, Suite A in Modesto. Or call (209) 525-6800. The office is open M-F 8:00 a.m. to 4:30 p.m.

Blog Focus

Posts for this blog will include seasonal gardening tips, posts on how to solve pest problems, and notices for events featuring the UCCE Master Gardeners.

Interested in Becoming a UCCE Master Gardener?

Visit https://ucanr.edu/sites/stancountymg/ to read about the program in detail. Our next class will start in January of 2020. Click on the big yellow button to fill out a survey to be contacted when sign ups for the class are available.