Peach Leaf Curl

From the garden e-mail bag, Kristi is not a big fan of curling (the disease, not the sport): "In the last two years I’ve planted several fruit trees. But right now, I am very concerned about my peach tree. It appears to have leaf curl. Everything I am reading on peach leaf curl tells me that I need to treat in the fall or the dormant season. I am wondering if it is OK to treat the tree with a fungicide now. Or, is it best to just leave it alone this year and treat it in the fall? Also, what is the best thing to use?"
  
Although it's still early, it looks like we have a 2011 winner in the informal, "What's Bugging the Backyard Gardener" sweepstakes: peach leaf curl. Just about everyone knows of a nearby peach or nectarine tree that is suffering greatly.
 
         


Peach leaf curl causes leaves of peaches and nectarines to discolor, thicken, pucker, curl, distort and eventually fall off. The fungus overwinters in these trees as spores, usually in the new buds. The rains of late winter and early spring - or in the case of 2011, the abnormally wet weather of March - splashed these spores onto the emerging leaves, causing more problems. Emerging shoots can die; fruit production can be reduced in severe infestations. Only rarely do reddish, wrinkled areas develop on fruit surfaces; later in the season these infected areas become corky and tend to crack.
 
         The good news is that a second set of leaves soon emerges and can develop normally when the rains cease and daytime temperatures steadily reach into the 80's. 

 


 Studies at UC Davis have shown that nipping off infected leaves of peach and nectarine trees doesn't do much good this time of year.
 
         






If your peach and nectarine trees are showing signs of peach leaf curl now, the best thing you can do is to assist those trees through this stressful period. 

• Rake up any fallen leaves and pull weeds that are growing beneath the drip line of the trees.

• Fertilize the area thoroughly, if you haven't yet done so. 

• Before the weather heats up into the 90's, spread four inches of fresh organic mulch beneath those fruit trees. Organic mulches, such as compost, shredded branches or the fallen leaves of healthy shrubs and trees will help conserve soil moisture, hold down weeds and add nutrients to the soil as that mulch breaks down.

• According to Steve Zien of the Sacramento-based organic garden consultancy firm, Living Resources, there now appears to be a method for control after the leaves have developed peach leaf curl.  Evidence indicates strong foliar applications of quality seaweed fertilizers (containing Ascophyllum nodosum) on distressed foliage can, in some cases stop the spread of peach leaf curl.

"Our findings indicate that foliar applications of seaweed (Maxicrop brand seaweed) can result in approximately 80% control of peach leaf curl," says Zien.  "A mixture of one part Maxicrop liquid concentrate to ten parts water was applied two to three times during early spring.  Following treatment new leaves developed normally.  Meanwhile, unsprayed trees and trees sprayed with water, continued to develop disease symptoms. Leaves damaged prior to treatment will remain distorted.  However, the leaf thickens, becomes greener and remains on the tree for a longer period of time (compared to untreated trees).  This provides the tree with vital nutrition until new healthy leaves develop.  One theory is that the seaweed thickens the cuticle (leaf skin) creating an environment not suitable for the fungus to develop." 

(2012 Note: Test results at the Fair Oaks Horticulture to control peach leaf curl during the winter of 2011-2012  showed the ineffectiveness of Maxicrop. "Compared to untreated branches, Liquicop-treated branches averaged about 70% control," says Chuck Ingels, Sacramento County Farm Advisor. "Copper soap was slightly better at 80% control, Agribon (row cover material)  by itself was less effective at just under 60% control, and both Agribon + Liquicop and lime sulfur (late fall) followed by Microcop (late winter) resulted in nearly complete control. Maxicrop (sea kelp) did not work at all and seemed to increase the severity on some of the branches.")
 
         The experts at UC Davis advise pruning infected peach trees in the fall before spraying with a copper ammonium complex product with 1% horticultural spray oil added to the mix.

     And now here's the bad news about sprays: the copper sprays available currently are weaker (about 8% concentration). Lime sulfur has been removed from the market. Bordeaux mixtures are expensive and wasteful...and potentially caustic.

In the good old days of fruit tree sprays (2009), 50% copper concentrates were the recommended course of action. Not any more.
The UC Davis Integrated Pest Management information on controlling peach leaf curl says, "Fixed copper products include tribasic or basic copper sulfate, cupric hydroxide, and copper oxychloride sulfate (C-O-C-S), but currently only liquid products containing copper ammonium complex products with 8% MCE (e.g., Kop R Spray Concentrate [Lilly Miller brands] and Liqui-Cop [Monterey Lawn and Garden]) are available to consumers. The most effective copper product, 90% tribasic copper sulfate with a 50% MCE (Microcop) is no longer available to retail outlets, because the manufacturer withdrew the product in 2010, although remaining supplies still can be sold."  

One of the reasons for that removal: repeated annual use of copper products over many seasons can result in a buildup of copper in the soil, which eventually can become toxic to soil organisms, and if it moves into waterways, can harm some aquatic species.


The removal of lime sulfur products was prompted by a rash of self-inflicted deaths in Japan in 2008 called "Detergent Suicides", which has since spread to the United States.


Bordeaux mixtures, a combination of copper sulfate, hydrated lime and water, are effective in controlling peach leaf curl, but come with their own set of warnings. According to the UC IPM Guideline entitled "Bordeaux Mixture":  "When applying Bordeaux, be sure to wear protective clothing, including goggles, because the spray deposit is corrosive, can permanently stain clothing, and is difficult to wash off." They also recommend wearing a dust and mist-filtering respirator when mixing in the hydrated lime. And that mixture can discolor anything it touches, including buildings and fences.


Although you can purchase pre-packaged Bordeaux Mixtures, they are not as effective as the mixture made from the individual components, reports that UC IPM Guideline. And that brings up the cost and waste involved: copper sulfate and hydrated lime are usually sold in large quantities, much more than the average homeowner needs for the backyard peach and nectarine trees. Storage involves mixing the leftover individual ingredients separately in water and storing in their own sealed jars. That UC IPM Bordeaux Mixture Guideline warns: "Be sure to clearly label both stock solutions and store them where children can’t get into them, since these materials, especially the copper sulfate, are very toxic and corrosive."

The synthetic fungicide chlorothalonil is the only non-copper fungicide available for managing peach leaf curl in the backyard orchard. Although one fall application may help prevent a spring outbreak of peach leaf curl, a second application in January or February, as the buds begin to swell, can be beneficial, as well.

But be sure to read and follow all label directions if you choose to use chlorothalonil, including this: 
"This product is toxic to aquatic invertebrates and wildlife. Do not apply directly to water or to areas where surface water is present or to intertidal areas below the mean high water mark. Drift and runoff from treated areas may be hazardous to aquatic organisms in neighboring areas."


Or this:  "May be fatal if inhaled. Harmful if swallowed or absorbed through skin. Causes moderate eye irritation. Avoid contact with eyes, skin or clothing. Do not breathe spray mist.


Or this: "This product contains chlorothalonil which is a
chemical known to the State of California to cause cancer."

No matter which spray method you choose, several days of dry weather must follow for the products to work. And that is one of the reasons the peach leaf curl breakout this year in Central and Northern California is so vexing: even though gardeners may have applied a spray, there were very few windows of opportunity (clear weather). If it wasn't raining this winter here, it was foggy. 
 
         There are peach varieties that are more resistant to peach leaf curl. The downside: they may not be as flavorful as you might like. Peach varieties reported to be more leaf curl resistant include Frost, Indian Free, Q-1-8 and Muir; among nectarines, only the Kreibich variety is resistant, says UC Davis.

================================ 


Saturday, April 30, 11 a.m.-1 p.m. See you at Davis Ace Hardware, 240 G. St. in Davis. Yes, there will be peach leaf curl questions. I'll be the one standing by the bags of Black Gold potting soil. Staring at a peach leaf sample.

===========================Sunday, May 1, 1-3 p.m. See You at Emigh Hardware, 3555 El Camino (just east of Watt). Come on out and let's talk gardening! Brought to you by Grower's Gold growing mixes.

Plants for Privacy

 

 "What can I plant to get some privacy?" That's a common question to the garden radio shows, especially from homeowners with small yards...and neighboring two-story homes.

 Here are some screening plants that can be a perfect fit for the Central Valley, lower foothills and the Bay Area of California. 

For quicker privacy,  don't install these plants on the outer edges of your property.

Plant them closer to the area you want to keep private.

For large yards, consider coast redwoods (Sequoia sempervirens). These evergreen trees can quickly overwhelm an area, getting over 50 feet tall and 15 feet wide at the base. Planted six or seven feet apart, coast redwoods will quickly

become a good screen. Be sure to plant coast redwoods at least 10 feet away from any fence or building.

Want a tree that looks like a willow without all the

problems? Try the Australian willow (Geijera parviflora). This evergreen tree with long, narrow, drooping leaves gets about 25 feet tall and 20 feet wide.

Incense Cedar (Calocedrus decurrens) 50-90' tall, 40-50' spread; evergreen; slow growth; takes heat, wind, drought.

 


Sweet Bay (Laurus nobilis) 30-40' tall, 20-40' spread.

Use its aromatic leaves for seasoning. Takes well to pruning.

Good container tree.

 
For a big yard, try the Calabrian pine (Pinus brutia or Pinus halpensis 'brutia' ) 30-80' tall, 15-25' spread.

For narrow areas:

Fern Pine (Podocarpus gracilior). 20-60 ft. tall, 10-20 ft. wide.

Thuja occidentalis "Emerald": 15 ft. tall, 3-4 ft. wide.

Juniperus scopulorum "Skyrocket": 15-20 ft. tall; 2-3 ft. wide. BUT...junipers need easy draining soil and can suffer from a wide variety of maladies, including spider mites, aphids, twig borers and blight.

SHRUBS FOR PRIVACY

For homes with planting areas about 15 feet wide, choose among these taller shrubs for privacy that  do well in our area. Plant them at least six feet away from any building or fence.

These are minimum hassle plants that will give your yard some privacy. All of these require full sun and regular water:

• Photinia (Photinia x fraseri). There's a reason you see these shrubs everywhere around here: photinia is a fast growing shrub whose established green leaves are complemented by the new, reddish-colored growth this time of year. Photinia makes an excellent privacy screen, getting eventually to 15 feet tall with an equal spread. For a smaller, slower growing variety, try the "Indian Princess". To get photinia to spread, pinch back new growth in the spring to encourage it to bush out.

• Bottlebrush (Callistemon citrinus). This plant, which produces red, brush-like flowers throughout the year, can take our heat and poor soils. Bottlebrush is fast growing and easy to train. Its flowers are attractive to bees and hummingbirds; so, people with aversions or allergies to bee stings should avoid this plant. On the other hand, if you're looking for a shrub that can get as tall as 15 feet that will keep the hummingbirds in your yard, the bottlebrush is for you.

• Evergreen Euonymus (Euonymus japonica). This plant gets 8-10 feet tall, and is considered a real garden "toughie". Euonymus can take lots of heat as well as poor soil. Many euonymus varieties have glossy, leathery, all-green leaves. But there are varieties that have more leaf color, such as the aureo-variegata, which has leaves with splashes of yellow surrounded by a green margin.

• New Zealand Flax (Phormium tenax). Any plant that can thrive in our south Sacramento County yard, an area that gets heavy wind, high heat and can still prosper in our rocky, clay hardpan gets my vote for plant of the year. Our New Zealand flax plants not only survive in those conditions, but came through like champs during the extensive backyard excavation, grading and remodeling work that took place near their roots three years ago. New Zealand flax can get to nine feet high with a six to eight foot spread. The long, sword-shaped vertical leaves have a brownish red color; other flaxes have colors that range from purplish-bronze to yellow. New Zealand flax works well as a screening plant, hiding unattractive (yet necessary) backyard equipment such as swimming pool pumps and filters.

• Clumping Bamboo. Good screening Bamboo varieties recommended by Madman Bamboo of Sacramento:
Bambusa multiplex "Golden Goddess"
B. multiplex "Alphonse Karr"
B. olhammii "Giant Clumping Timber Bamboo"


VINES FOR PRIVACY

For narrow areas, a vine may be what you need for privacy. Construct a sturdy trellis, perhaps on a short wall or fence. 

A good, evergreen vine for that trellis in full sun is Carolina jessamine (Gelsemium sempervirens). It produces yellow flowers in the spring. 

Other evergreen vines to consider include:

crossvine (Bignonia capreolata), 

evergreen clematis, 

violet trumpet vine (Clytostoma callistegioides), 

common winter creeper (Euonymus fortunei radicans),

lacevine (Fallopia baldschuanica), 

jasmine, 

trumpet honeysuckle (Lonicera sempervirens), 

mattress vine (Muehlenbeckia complexa),

passion vine (Passiflora jamesonii), 

potato vine (Solanum laxum), 

and star jasmine (Trachelospermum jasminoides).

Potato Vine

The 2010 Tomato Report Card

 If you haven't picked out your tomato plants yet, here's a guide to what happened here in our tomato garden in Sacramento last year. But the 2010 tomato year may not be the best barometer for choosing your 2011 tomato plants.

 Was there a summer in 2010? You wouldn't think so, judging by the erratic to poor quality of the homegrown tomatoes last year here in many parts of  California's Central Valley. The 2009 Tomato Report Card hinted that "all bets were off" for 2010, due to the unseasonably cool weather through May (plus rain at the end of the month). And sure enough, it stayed abnormally cool through June and July. 

Average daily maximum high temperatures last spring and summer for Sacramento, compared to the historic average for those months (in parentheses):
April 2010: 66 (73)
May 2010: 75 (81)
June 2010: 87 (88)
July 2010: 91 (93)
August 2010: 92 (92)
Sept. 2010: 88 (88)


No wonder the tomatoes didn't go full-tilt boogie into production until August and September! So, keep in mind the wacky weather of 2010 as you peruse last year's Tomato Report Card here at the Farmer Fred Radio Ranch:


Lemon Boy A  Excellent. long production cycle, good flavor

Dr. Wyche

Dr. Wyche A  Best heirloom of 2010

First Prize B+ Good producer early on. Everything the Celebrity should have been.

Sweet Gold B+ - Dependable yellow cherry tomato 

Early Wonder B  Did better than Early Girl; larger, too.

Beefmaster

Beefmaster B-  Erratic production but good size

Big Beef  B- Dependable slicer.

*Poti Cuote Bue-1  C+  produced early, nothing to write home about.

Cracking on Poti-2

*Pomodoro Canestrino  C+ Juicy but went bad quick

*Poti Cuote Bue-2 C  less productive than PCB-1. Subject to cracking.

   

Solar Yellowing on Viva Italia

Viva Italia C  Sunburn, solar yellowing, produced late.



Djena Lee’s Golden Girl  C  Disappointing, with little production.
 

Blossom End Rot

*Pomodoro Canestrino Red Pear ‘Claudia’ C-  Firmer, but gets blossom end rot easily. 




Bloody Butcher C-  Not as productive as 2009

Early Girl C- Didn't produce until August. Tiny.

 

Where's Marianna?

Marianna’s Peace D Little production but tasty. Went bad quick.

Celebrity F - I swear, it was NOT a Celebrity. Ping Pong Ball size. Gangly vine, little production. 2010 was the third year in a row of disappointment for this All America Winner. Before then, it was one of the best.




* Yes, these are weird names. My daughter vacationed in Italy in 2009, staying with a family in central Italy, who gave her these seeds, wrapped in aluminum foil. Their names were probably lost in the translation. This much I know: "pomodoro" means "tomato" in Italian. "Canestrino"is a plum variety of tomato. "Poti Cuote Bui" is probably Petit Coeur de Boeuf.


A link to previous years in our garden.

Gearing Up for the Cherry Maggot Battle

"Cherry Maggots Come To Town" would be a great name for an indie band. Unfortunately, this is one insect you don't want performing in your yard. The spotted wing drosophila (SWD), is responsible for the little worms that backyard gardeners are starting to find in their cherries, and to a lesser extent in raspberries, strawberries and blueberries. First spotted in Santa Cruz County in 2008, this pest is now throughout the West Coast, and has been spotted recently in traps in Sacramento County and the surrounding area.

According to Sacramento County Farm Advisor Chuck Ingels, the adult SWD is small (2-3 mm), resembling a gnat that might be found on that old piece of fruit on your kitchen counter. This one, though, has a sharp ovipositor (sort of a needle-like, egg-laying device) that penetrates ripening fruit...such as your backyard cherries, that are developing now for a May-June harvest.

 Adult male spotted wing drosophila, Drosophila suzukii, (2-3 mm long) has a dark spot on each wing tip.
Photo by Martin Hauser.

Adult female spotted wing drosophila, Drosophila suzukii (2-3 mm long).
Photo by Martin Hauser.

This pest might easily be confused with a vinegar fly or the western cherry fly. Western cherry fruit fly adults are much larger (5 mm) than the spotted wing drosophila adults and have a dark banding pattern on their wings. The western cherry fruit fly, which is a quarantine pest, occurs in Washington and other states but has not established in California. 

Here is a detailed description of the SWD, according to an excellent report produced by the  UC Integrated Pest Management Website on Spotted Wing Drosophila: "Adults are small (2-3 mm) flies with red eyes and a pale brown thorax and abdomen with black stripes on the abdomen. The most distinguishable trait of the adult is that the males have a black spot towards the tip of each wing. 

Larvae are tiny (up to 3.5 mm), white cylindrical maggots that are found feeding in fruit. One to many larvae may be found feeding within a single fruit. After maturing, the larvae partially or completely exit the fruit to pupate."

Among you are those who are starting to ask the question, "What garden insecticide can I buy to stop this pest...."

Let me stop you right there. The cure may be worse than the problem. Limited research has been done on this new invader to California, and the chemical that so far has been found to best control the adult spotted wing drosophila is deadly to one the best "garden good guys" around, the honeybee.

The UC IPM Website says: "Although malathion...has been shown to control the adult SWD, coverage would need to be so thorough throughout the entire tree. Malathion is very toxic to bees and natural enemies of other pests in the garden, so care must be taken to keep the application on the tree and avoid drift and runoff. Improper application can also result in injury to the tree. Application should be made about 2 weeks before harvest. Sprays must kill adults before they lay eggs. Malathion will not control larvae in fruit. 

An alternative to malathion with fewer negative environmental effects would be spinosad (Monterey Garden Insect Spray); however, it is not believed to be as effective against the fruit fly adults as malathion. Two sprays may be required at about 14 days and 7 days before harvest to get satisfactory control. As with malathion, all foliage and fruit on the tree must be covered with the spray. Partial coverage will not be effective. A compressed air sprayer will give more reliable coverage than a hose end sprayer."

Two better, safer options: dispose of infested fruit and set up traps, reports the UC IPM site: 

"Spotted wing drosophila attacks ripening fruit, and unfortunately is often not noticed in backyard trees until fruit is being harvested. Sprays at this time will not protect the crop, because maggots are already in the fruit. If only some fruit are infested, you can salvage some of the crop by harvesting the crop immediately and sorting, removing fruit with stings on the surface. Place infested fruit in a sturdy, sealed plastic bag and dispose of it in the trash. Also remove any fruit that has fallen on the ground and any infested fruit remaining on trees—this may reduce populations of flies that might infest next year's crops or later ripening varieties. In addition to placing infested fruit in the trash, it can also be buried. Composting may not be a reliable way to destroy eggs and larvae in fruit."

The report from UC goes on to say, "There is some evidence from research done in Japan in the 1930’s that traps can be used to manage SWD in backyard trees. Some trials on this method will be undertaken this summer. To try this method for yourself, make traps out of one quart plastic yogurt containers (with a lid). Drill 16 holes that are 3/16-inch in diameter around the top of the container. Bait each trap with a solution of 1/4 cup grape wine plus 1/4 cup water plus 3/4 teaspoon of molasses. In early May, about 1 month before harvest, hang 3 to 5 traps in a shady spot on the lower branches of the tree. Keep the traps up until harvest is completed. Refresh the bait if needed. These traps can also be used to detect SWD in your garden earlier in the season. Bait the trap with about an inch or 2 of white wine. Check the trap weekly for small flies with dark spots at the tip of their wings floating in the fluid. These are male SWD and will confirm that you have the pest."

Netting. "Netting may be useful to keep flies from attacking fruit on blueberries and other small fruit or possibly branches on small trees. However, the netting must be applied before fruit begins to ripen so that flies will not be caught inside the net. Netting must be secured at the bottom so flies cannot enter, and the mesh size should be very small."

Early Harvest. "Early harvest can be important in reducing exposure of fruit to the pest. Begin harvest as early as you can and continue to remove fruit as soon as they ripen." 

And, as that would imply, choosing cherry trees with an early harvest date may minimize problems with the spotted wing drosophila. "Usually the earliest harvested cherries get the least damage," says that UC report. Here in the Sacramento and Northern San Joaquin valleys, early ripening cherry varieties include Minnie Royal, Black Tartarian, Royal Lee, Craig's Crimson and Royal Ranier, according to wholesale fruit tree grower, Dave Wilson Nursery.

The bottom line: good sanitation - cleaning up and disposing of fallen fruit and vegetables - goes a long way to thwarting many backyard pests.

How To Kill Your Lawn in 2 Easy Steps

 

1. Mow the lawn as short as possible.

 

2. Top the area with 12 inches of small wood chips or chipped/shredded tree limbs.

In a few weeks, you should have soil suitable for planting something other than a lawn. Preferably, putting in plants that are a lot less work, are edible and/or use less water, fertilizer and pesticides.

According to Washington State University Horticulture professor Linda Chalker-Scott:

"Double digging the soil 12 inches isn't necessary," explains Chalker-Scott on her blogsite, The Garden Professors.  She goes on: "Double digging the soil 12 inches destroys soils structure...Sheet mulches impede water and air movement.  They're not needed to keep the grass from growing through. Wood chips do this just fine on their own. And don't worry about that initial 12 inches of chips. Within a few weeks it will settle to about 8 inches. Let it sit for several weeks. Then pull aside some of the chips and take a look. If the process is done, the grass and/or weeds will be dead and decomposing - a natural compost layer. You can then plant whatever you like. Reuse the chips somewhere else in your garden."

This is not an inexpensive process, costing about $1.30 per square foot of lawn area you want to cover. For a 12-inch layer of small bark to cover 100 square feet, you would need four cubic yards of bark. In our area, that would cost you about $130, plus taxes and delivery. And that's just to cover 100 square feet!

I would be inclined to leave that mulch in place for several months, if not a full year, to make sure the lawn is dead.

Other reasons to leave that mulch on as long as possible: those small wood chips/chipped-shredded tree limbs are slowly breaking down, feeding the soil, improving the tilth (a healthy combination of nutrient-rich soil and air pores) and increasing microbial activity in the growing zone. Plus, it isn't bad to look at, either.

There is another down side to this process: 12 inches?!? That's one hell of a first step UP to your former lawn. And then your shoes get buried.

Other ways to kill a lawn: soil solarization (limited to use during the summer); and, America's most popular method to kill unwanted plants: applying glyphosate (aka Roundup). But the more you read about glyphosate, using non-chemical means to rid yourself of a lawn looks better and better.

 

No matter which lawn-killing process you use, remember Farmer Fred Rule #7: Bermudagrass is forever.