Citrus trees need care throughout the year, including cultural practices to keep trees healthy and pest management. During the fall season, several pests can attack citrus trees in many California regions.
Brown Rot
Monitor for this disease by checking for damaged fruit on your tree, as well as fruit in storage. Sometimes affected fruit develops a pungent odor and can ruin fruit held in storage. See the UC IPM web page on Brown Rot to learn more.
If you see what look like small “tunnels” on your citrus tree leaves, your tree might have citrus leafminer. The adult stage of this pest is a small, light colored moth; the larval stage feeds and develops inside the leaves of young citrus and other closely related plants.
Citrus leafminer rarely causes problems for mature trees, however, it can seriously damage very young trees. Read the UC IPM Pest Notes: Citrus Leafminer for recommendations for prevention or management.
Snails and Slugs
Asian Citrus Psyllid and Huanglongbing
You may have heard of the Asian citrus psyllid (ACP) and the deadly disease huanglongbing (also called citrus greening) that has been featured in the news. This disease doesn't pose a threat to humans or animals, but is deadly to citrus trees. Once a tree develops huanglongbing, there is no cure, so for this disease prevention is key.
UC IPM Web Site
For information on managing other citrus pests in the garden, see the UC IPM webpage on Pests in Gardens and Landscapes: Citrus.
- Author: Denise Godbout-Avant
People often rake their leaves and put them out to be picked up as trash. I have always preferred to leave the leaves for my garden.
If you take a walk in a forest, you'll see leaf layers several inches deep around trees and bushes. Fallen leaves have a complex relationship with trees and nature, providing many benefits which can be reproduced to some extent in our gardens.
Natural Mulch
Fallen leaves have the same weed suppression and moisture retention properties of shredded wood mulch—and they're free! Where mulch is desired as a decorative element, what could be more seasonally appropriate than a pile of brightly colored fall leaves? This natural mulch also provides insulating winter cover from cold temperatures for roots, seeds, and bulbs.
A Web of Life in Leaf Litter
Leaf litter isn't just free fertilizer and mulch. It provides food and shelter for a wide variety of living things including spiders, snails, worms, beetles, millipedes, mites, toads, frogs and more—these in turn support mammals, birds, reptiles, and amphibians that rely on these creatures for food.
Detritivores (organisms that eat dead or decaying plants or animals) break up and excrete leaf litter. Fungi and bacteria then take over and complete the recycling process converting these smaller pieces into nutrients which then sustain neighboring plants. They in turn help support biodiversity by becoming food themselves.
Numerous bird species such as robins and towhees forage in the leaf layer searching for insects and other invertebrates to eat.
Raking up leaves and putting them in the trash could have the unintended consequence of removing some of next year's garden butterflies and moths, many of which are pollinators. Most butterflies and moths overwinter in the landscape as an egg, caterpillar, chrysalis, or adult. In all but the warmest climates, they often use leaf litter for winter cover. Fritillaries and wooly bear caterpillars will tuck themselves into a pile of leaves for protection from cold weather and predators. Some Hairstreaks lay their eggs on fallen oak leaves, which become the first food of the caterpillars when they emerge. Swallowtail butterflies disguise their cocoons and chrysalises as dried leaves, blending in with the “real” leaves.
Bumble bees also rely on leaf litter for protection. At the end of summer, mated queen bumble bees burrow an inch or two into the earth to hibernate for winter. An extra thick layer of leaves is welcome protection from the elements.
All of which makes leaf litter an integral part of a complex web of life.
What You Can Do
Composting leaves is a terrific way to recycle and create a nutrient-rich garden soil amendment at the same time. Some gardeners opt for shredding their fall leaves for use in compost piles. Like people who mulch their lawn leaves with a mower, consider leaving some leaves undisturbed in garden beds and lawn edges. If space allows, you could create a leaf pile, allowing it to break down naturally, or add the leaves gradually to your compost pile over time. Such efforts will keep leaf litter critters safe and allow you to benefit from the rich garden gift that falls from the trees above.
While it is ideal to “leave the leaves” permanently—for the benefits mentioned above—if you do decide you need to clean your garden and remove the leaves in spring, try to wait until later in the season, so as to give the critters that have been protected by fallen leaves over the winter time to emerge and depart.
Some gardeners may be concerned that autumn leaves, matted down by rain or snow, could have a negative impact on their perennials. However, a thick layer of leaves provides additional insulation against chilly weather and protects newly planted perennials from frost which could damage tender roots and shoots. Anyone who has spotted fragile spring seedlings popping up in the woods knows that all but the most fragile of plants will erupt through the leaf litter in spring without trouble.
So, leave the leaves. While you can't perfectly emulate a forest, your garden will be healthier and more diversified, you'll help support a vast array of wildlife, and you'll reduce the strain on landfills.
Denise Godbout-Avant has been a UCCE Stanislaus County Master Gardener since July 2020.
/h3>/h3>/h3>- Author: Denise Godbout-Avant
Why do some trees change color and drop their leaves before winter? And why are there different colors?
Leaves are colored by pigment molecules. Most leaves appear green because they contain an abundance of the pigment chlorophyll. Chlorophyll is the site of photosynthesis where the sun's energy is converted into the carbohydrates that are plants' food source. During the cold winter months when there is less sunlight, it would take too much energy for some trees to keep their leaves healthy. So deciduous trees lose their leaves for the winter. Evergreen trees have a different strategy for dealing with winter's challenges (which is a topic for another time!).
Elevation, latitude and weather all affect the timing and intensity of fall colors. Higher elevations and northern latitudes produce earlier autumn colors in trees. In general, autumn weather with lots of sunny days, dry weather, and cold, frostless nights will produce the most vibrant palette of fall colors. Some trees that can produce vivid colors include maples, gingkos, aspen, birches, Japanese maples, liquidamber, cherry, redbud, Chinese pistache, and dogwood.
In the Central Valley we usually don't get the glorious colors like the Sierra Mountains or the east coast, but we do get some color which usually starts in early November. So, enjoy the autumn jewels since it occurs only for a brief period each fall!
Denise Godbout-Avant has been a UCCE Stanislaus County Master Gardener since July 2020.
When: Tuesday, August 25, 2020 from 6:00-7:30 p.m.
Where: on Zoom.
Please sign up to receive the link by August 25, 2020 at 4 p.m.
If you don't have Zoom or have to miss the class, watch it later on our Stanislaus County UCCE Master
As a gardener, I get really excited to plant some of my favorite foods. Broccoli, cauliflower, swiss chard, kale, and lettuce always grace my table each fall and into the winter months. Carrots and sugar snap peas greet me next to my front door. Green and purple cabbage have even lined my walkway tempting me with thoughts of the sauerkraut that will be made from their crunchy heads.
While the majority of my experience has been with planting my veggies in raised beds and in ground, when I was first starting out on my gardening venture I planted several varieties in pots and containers. Lettuce, carrots, sugar snap peas, have all grown well for me in containers.
The best thing about growing lettuce, especially romaine, is that you can harvest the lettuce throughout out the season. By snipping off the older, outer leaves, you can keep your lettuce growing and extend your harvest. I usually sow my seeds every two weeks just to make sure I have lettuce all fall and winter long.
Sugar snap and snow peas are great for containers. I've normally use transplants from the nursery but seeds will work just as well. Choose a container that is quite sturdy as these peas like to have a trellis to grow upon. Place a homemade trellis in the pot and place your transplants or seeds about two inches away from the trellis. Alternately, I have placed my peas in pot next to a pretty trellis leaning against the garage wall and they have loved it. The best thing about growing peas is the more you harvest, the more they produce.
Carrots, for me, are a little trickier. First time I tried them the container wasn't deep enough and I had these little stunted carrots. Choosing a deep container or pot, at least 12” led to better success and a very tasty treat. Remember to thin out your carrots as well or you'll have some very interestingly shaped and twined carrots. They are still edible, but don't look very pretty.
Yes, fall is one of my favorite times of year. Not just for the weather, but for the abundance of produce that we can grow here in the Central Valley. Fall veggie container gardening is a great way to get started on your adventures in gardening.
Terry will be co-teaching our upcoming Fall Vegetable Gardening class on August 25. Save the date! More details coming soon.