If you have a peach or nectarine tree in your landscape, most of the leaves have probably dropped. This is a great reminder to gardeners that it's time to spray for peach leaf curl.

Why spray for peach leaf curl disease?

Right now, the fungus that causes leaf curl is present on your trees. Once spring arrives, its spores “move” via water droplets splashed onto developing leaves. When the environment is right, these spores invade newly developing leaves, growing in between leaf cells and causing distortion of cells.   

Symptoms of peach leaf curl disease include puckering leaves that curl and turn a reddish color. Often the entire first set of leaves may drop off. When new leaves begin to grow, these leaves are also infested. Twigs and shoots distort and often die. Fruit is rarely affected. However, left untreated, nectarine and peach trees begin to decline and fruit production is substantially reduced.

Often when gardeners see symptoms of leaf curl disease on their tree, they are tempted to pull off the affected leaves, thinking this will help. Unfortunately, there is little to do at this point to control the disease.

Prevention

The only way to prevent peach leaf curl disease is to protect your tree with a preventive spray. This is done once during the dormant season using a copper-based fungicide. However, during wet winters you may want to spray a second time late in the season before green leaf tips begin to show.

Using Pesticides

Insects, diseases, and weeds are pests, and products used to kill them are called pesticides. Whether a product is organic or not, it can still have an impact on you and/or the environment, so be sure to follow the directions on the product label regarding personal protection, correct mixing, and application. When spraying, make sure to coat the tree until the product is dripping off. Come spring, your peach and nectarine tree trees should leaf out and grow vigorously, followed by a healthy crop of fruit.

Learn more about peach leaf curl by visiting the UC IPM website and reading their Quick Tips on it at http://ipm.ucanr.edu/QT/peachleafcurlcard.html  For more detailed information about this disease, read the Pest Notes at http://ipm.ucanr.edu/PMG/PESTNOTES/pn7426.html

Coming Soon

Bare root fruit trees are arriving in nurseries and garden centers. If you are thinking about planting fruit trees but aren't sure what to plant, how to plant, and how to care for them, you'll want to attend our online Bare Root Fruit Tree Planting and Pruning Class on January 25, 2022. More details coming next week.

If you have fruit trees that produce a lot of small fruit, you may be missing an important step in growing fruit trees called "thinning." Next month we'll publish an article on how and when to thin fruit from Ed Perry, retired UCCE Stanislaus County Emeritus Horticulture Advisor.

Anne Schellman is the UCCE Stanislaus County Master Gardener Program Coordinator.

 

 

 

January has always been my least favorite month of the year. The often dreary, short, gray days seem especially dull after all the December festivities. Going outside to work in my garden is a chore when I'd rather be snuggled under a blanket with a good book in front of a fire with a hot drink. However, there are many important gardening chores that should be done during the cold winter days.

Seasonal Landscape IPM Checklist for Home Gardeners

UC's Integrated Pest Management (IPM) Home, Garden, Turf and Landscape Pests Quick Link has a Seasonal Landscape IPM Checklist which is a wonderful resource with monthly checklists within your selected county/region to help guide you how to keep your landscapes healthy. 

https://www2.ipm.ucanr.edu/landscapechecklist/

Topics include common pest problems to look out for, preventative measures, and links to more information. You can also subscribe to receive an automated monthly list by email. 

December and January Lists

I reviewed the December and January checklists for Stanislaus County. The following are some topics listed and additional appropriate links:

• Frost – Temperatures sometimes drop to freezing during the winter months. Cold temperature can kill bark, buds, flowers, and shoots, so protect sensitive plants from frost.  To increase a soil's ability to absorb heat rake away mulch to expose the ground around the base of the plant. If frost is expected irrigate the soil (if there hasn't been any rain recently) at least three days prior. You can also cover sensitive plants overnight with cloth or similar material other than plastic but leave covers open at the bottom so heat from soil can help warm plants and remove covers during the daytime. http://ipm.ucanr.edu/PMG/GARDEN/ENVIRON/frostdamage.html
• Irrigation – Always adjust your watering schedule according to the weather. We have had a very wet December, which followed an atmospheric river storm in October. So, gardens have needed little to no irrigation lately, depending on your soil type. Overirrigation can lead to root rot. Resume irrigation if storms diminish during the remainder of the winter (let's hope it remains wet!). If there is an extended dry spell during upcoming winter months, irrigate infrequently and deeply. http://ipm.ucanr.edu/homegarden/irrigating/
• Clean up – Remove old fruit and nuts in and under trees to avoid harboring pests. Also rake up fallen leaves beneath deciduous fruit trees and roses (but leave the leaves elsewhere in your yard for beneficial overwintering insects including butterflies and bees). http://ipm.ucanr.edu/PMG/GARDEN/FRUIT/CULTURAL/sanitation.html
• Prune – Trees and shrubs that need pruning including apple, crepe myrtle, pear, rose, spirea, and stone fruits (exception are apricot and cherry trees which can harbor certain pests, i.e. shothole borer, which should be pruned in the summer). Remove dead and diseased wood. http://ipm.ucanr.edu/homegarden/pruning/ 
• Mistletoe – Mistletoes are parasitic plants that absorb nutrients and water from a host tree. Healthy trees can tolerate a few branches infected with mistletoe, but a heavy infestation could ultimately kill a tree, particularly if the tree is stressed or unhealthy.  With leaves having dropped during fall months from deciduous trees, mistletoe is visible on the now-bare trees, and thus can be removed easily. Remove branches at least a foot below the mistletoe attachment before it produces seeds that will infest other limbs and trees. Since mistletoe often infects many trees on the same street, a neighborhood effort to remove all mistletoe from any trees on the block will help reduce continued spread in the area. http://ipm.ucanr.edu/QT/mistletoecard.html
• Peach leaf curl –If leaf curl has been an issue on your peach or nectarine plants apply preventive spray once or more times until bud break. http://ipm.ucanr.edu/QT/peachleafcurlcard.html
• Bare root plants – Now is the time to plant bare root deciduous trees, shrubs, and vines, including roses, fruit, nuts and grapes. Select species and cultivars that are appropriate for the site it is being planted. http://ipm.ucanr.edu/homegarden/planting/

This compilation is a partial overview of the lists I reviewed. Check out the January seasonal landscape checklist for your area to see which tasks you need to do. Then bundle up, get your garden tools, and go outside (preferably on a sunny day!) to do the necessary winter maintenance chores in your garden. You and your landscape will be rewarded for your cold weather efforts come spring.

 Denise Godbout-Avant has been a UCCE Stanislaus County Master Gardener since July 2020.

It's a cold winter's day here in the Central Valley. But instead of curling up in a cozy chair with a cup of tea, I'm out in my garden, planning and prepping for my spring planting. For me, this is the fun part, walking the gardens, looking at the raised beds, empty pots, and bare earth. I imagine what I'll place where, and jot down what needs to be done to prepare these spaces. Then it's inside to peruse the seed catalogs and online sites, make notes, and dream about the coming spring.

Planning your garden now, I feel, will save you headaches and money, come spring. By taking the time to understand how much space you have (or don't have), whether or not you wish to plant directly in ground or containers, or a combination thereof, and what types of plants grow best in your area, you'll only purchase what you need. In addition, you can decide whether or not you wish to devote the time to starting your seeds indoors or in a greenhouse, plant the seeds directly in the garden beds, or if transplants are the way you wish to go.

Some other things you'll need to take into consideration when planning your spring garden is how much sun you have in each of the proposed planting areas. If uncertain, take a look at the surroundings now. While you'll not be able to gage precisely how much sun they'll have come spring and summer, you can take note of things that could possibly shade them or hinder the sun from reaching them. Are there a lot of trees in the area that will shade them once their leaves have returned? Will that patio cover keep the sun from reaching them? Perhaps the arbor next to the west bed will be covered in greenery when the Wisteria blooms, blocking out the sun. If you are contemplating shade plants, are there locations that may be too sunny for them? Taking the time to scope out the positioning for your new plants will give them the best chance to grow and thrive.

If you are thinking of planting spring veggies, take under consideration what you and your family will actually eat. If the kids detest string beans, then planting a huge area full of them is probably not a good use of the space, your time, or money.  However, if zucchini is something you eat frequently, then two mounds may serve you better than one.

Winter is the best time to prepare your planting areas for your spring garden. Whether you are planting flowers, or veggies, in raised beds, containers, or in ground, getting your soil ready now is key. The time you spend this winter prepping and amending means that you'll be able to plant immediately once the threat of frost has passed (usually around mid-March here.) In addition, placing amendments, such as steer or chicken manures, in your garden now will give them a chance to “mellow” and break down, so that the soil is ready for transplants and/or seeds.

Now is also a good time to get control of any weeds in your proposed planting areas. Removing any weeds now, before the weather gets warmer and they decide to seed, means less work for you come spring and summer. I like to get down, move the soil with a trowel, and pull out any stray roots or seeds that I see. You may even find grubs and larvae of Hoplia beetles that you can remove, saving your precious roses and flowers this spring.

Many of us reuse our favorite pots and containers year after year. As such, these pots will need some TLC and prep as well. All the old soil will need to be removed and the pot cleaned with a solution of one-part bleach to nine parts water. Submerge in solution and soak for at least 10 minutes. This sterilizes them, removing any insects or diseases from the previous plant in the pot. 

Planning and prepping your garden now for your spring planting will give you that head start to a successful, satisfying, and fun gardening adventure. So, get out your seed catalogs, notebook, and take a walk in your yard or garden space, and imagine all the possibilities. Happy Gardening!

Autumn is the favorite season for many people. The days are shorter, the weather cooler, the bright blue skies of summer fade to a softer blue with clouds, and the leaves of some trees start presenting their autumn glory. 

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!).

Temperature, precipitation, and soil moisture are all factors which contribute to plants dropping their leaves in autumn, but the primary agent is light, or rather, the lack of it. After the autumn equinox, the shorter days with longer nights triggers chemical changes, causing the tree to seal off vessels that supply the leaves with nutrients and water. The combination of reduced light, lack of nutrients, and less water starts the process of the green chlorophyll to break down. As the green fades, the other pigments in the leaves, which were present all along, but were masked by the green chlorophyll, begin to reveal other bright pigments. In time the leaf is blown off from the sealed cut, or falls from its own weight. 

Leaves containing primarily anthocyanin pigments will appear red. Carotenoids can be orange, yellow or red. Xanthophylls are yellow-brown. Some leaves, like oaks, contain tannins which will produce brownish colors. A chemical process called paper chromatography of a plant extract will separate the various pigments present which can reveal some of the pigments found in leaves. This photo illustrates pigments found in mint leaf extract.

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.