Why Are the Blackberries Turning White?

From the garden e-mail bag, Teri asks: "What is wrong with my blackberries?"

Dewey & Ann write: "What is causing this problem with my Chester blackberries? This is on the majority of them.  I had it last year too. I checked with the local Hmongs and they also had it and said it was the 111 degrees we had in Oroville. We are at 2500 feet and 10 degrees cooler, but it wasn’t this hot last year. My Black Satin Blackberries were forming and doing well and I thought the problem was only with the Chester. Well, pretty soon I see it on them also. Am I missing something in our soil? It’s not on every one of them. It’s a dried seed eventually, but goes from a pink to beige and then worse if you don’t pick them. I would like to get to bottom of this. Can you help me?"

Your local Hmong are wise gardeners. The recent week of very sunny 100+ temperatures, along with a couple of triple digit scorchers in the first week of June, could very well be the culprit.

Usually when we think of heat stressed plants, the cool season ones that tend to croak when it gets hot come to mind...

 

Such as lettuce...


















Or sweet peas.

 
Even warm season vegetables that like sunlight, especially tomatoes, can be adversely effected by too much high intensity sun. Abiotic disorders such as cracking, solar yellowing or green shoulders are common this time of year on young tomato crops.

Solar Yellowing

Cracking

One remedy for that: don't prune off any of the leaf canopy of tomato plants; or, cover with a lightweight row cover to provide some more shade.






















And now, you can add blackberries to the list of crops that develop problems when it gets too sunny, too hot, dry and windy, especially this year. The problem is known as White Drupelet.

According to the UC Integrated Pest Management Guidelines for Caneberries:
"White drupelet is a tan-to-white discoloration of one to many drupelets on the fruit. Most often, white drupelets will appear when there has been an abrupt increase in temperature accompanied by a drop in humidity; it is especially pronounced when there is wind. In the Monterey Bay area, white drupelet typically occurs when temperatures that are fairly steady around 70 degrees suddenly go above 90 degrees, and there is an absence of fog.

While white drupelets may seem to be directly caused by weather, they are actually caused by ultra-violet (UV) radiation. Weather conditions modulate this by the effect they have on penetration of UV radiation into the fruit. Cool, humid air scatters and absorbs UV radiation, while hot dry air has the opposite effect and allows more direct UV rays to reach the fruit. The movement of humidity away from the canopy by wind only heightens the effect of hot dry air. Additionally, as humidity is moved away from the plant canopy, more UV rays penetrate the canopy and damage fruit that may not even have been exposed to the sun. Fruit inside of the canopy is not acclimatized to UV radiation and is subsequently more susceptible when it reaches them.

Some growers of caneberries in the Willamette Valley of Oregon, where rapid changes from a normally mild climate to temperatures up to and above 100 degrees occur through the summer, use overhead irrigation to minimize fruit loss to white drupelet. This is not merely to mist the fruit; instead, large amounts of water are applied to thoroughly wet the canopy and maintain cool temperatures and high canopy humidity for as long as possible. Sprinkling is not done too late in the evening to allow fruit to dry before nightfall.

While some varieties, such as Apache blackberry, Kiowa blackberry, and Caroline red raspberry tend to get white drupelets more frequently than others, almost all caneberry varieties are susceptible to white drupelet to some degree."

Hey, blame it on the weather.
 

Garden Tasks To Do, and NOT Do, This Fall

Columbus Day, Halloween, Veterans Day, Thanksgiving, Hanukkah, Christmas. The busy holiday season awaits. OK, maybe you aren't going to get dressed up as the "Santa Maria" and march down Main Street on October 8, but there are still enough other tasks to accomplish this time of year to dissuade you from the garden. The good news: here are some yard chores you don't have to tackle this time of year.

• Don't deadhead your roses. Many Northern California rosarians are now advising rose growers to let those fading October flowers remain on the plant. This will force the rose bush to form hips, which helps the plant slow down in preparation for the January pruning season. Because cold winters are not a certainty here, roses have problems entering complete dormancy in our area. Not pruning roses now tells the plant, "Time to take a nap!"

• Don't prune your shade trees until the last leaf has fallen. Then, it will be easier to gaze up into the canopy of the tree to decide which branches need to be trimmed or removed. Good reasons for pruning trees include removing or cutting back branches that are rubbing each other or the house. Low branches that impede foot traffic or suckers emanating from the base can be removed at that time, too. If you think you won't remember the dead branches that will need to be removed when all the leaves are gone, go ahead and mark those branches now with ribbon or green tree tape.

• Don't Prune Citrus Trees. Lance Walheim, author of the books "Citrus" and "All About Citrus & Subtropical Fruits", says early fall is the one season to avoid taking a saw to your orange, lemon, mandarin and other citrus trees. The soil is still warm, which will push out new growth wherever you made a pruning cut. And that new growth will be more susceptible to frost damage during the late fall and winter.

• Don't Prune Apricot and Cherry Trees. Apricots and cherries are susceptible to Eutypa dieback, a disease which kills branches. Infection occurs on wounds made during wet weather. You need six weeks of dry weather after pruning. Prune these trees after harvest in late spring or early summer.

 

And now, for you masochists, some autumn garden tasks to add to that growing list on the side of the refrigerator.

• Clean up the summer vegetable garden. Many garden pests overwinter in fallen fruit and twigs, too.

• After you've cleared out the dying summer vegetables, prepare for next year's garden by checking the soil pH. Test kits are available at just about every nursery.

  •  Tomato hornworms are going into hibernation in the soil beneath your tomato plants. Dig down about four inches and discard their cocoons, which resemble two inch-long, reddish footballs.

• Feed your bare garden soil during the winter with a cover crop of clover, fava beans or vetch. This will add nitrogen for next year. 

Chinese Pistache

 • This is a great time for planting new trees and shrubs, especially ones with outstanding fall foliage for California. Good specimens include Japanese maples, Chinese pistache, tupelo, red oak and scarlet oak.

  
• Vegetables to plant from seed now include radish, spinach, fava beans, carrots, swiss chard, corn salad, leaf lettuce, onions and peas.

•  Despite the cooler temperatures, your lawn and garden still need about an inch of water a week. Unless the rains come, keep your automatic sprinklers operating. How much water is an inch? Here’s how to measure.

•  Cool season lawns, such as the popular fescue blends, are putting on a spurt of growth now. Mow often so that you are never removing more than a third of the total height of the grass blade.

 • Dethatch, aerate and overseed bermuda grass lawns with rye grass to keep it green all winter. At a loss of how to start? Here’s how.

•  This is a good time to plant ground covers such as low growing manzanitas, verbena and carpet bugle. This will give their root systems a chance to get established for their burst of spring growth.

• Scatter and plant tulip and daffodil bulbs outdoors for a more natural look.

• Add some indoor color for the upcoming holiday seasons by planting bulbs in containers. Your favorite local nursery has a good supply right now.

• Feed and protect rhododendron and azalea roots during the winter by adding two or three inches of mulch around those plants. More on the benefits of mulch.

• Available now at nurseries: colorful winter blooming annuals such as violas, calendulas, stock, Iceland poppies and snapdragons.

 • Temperatures dipping down below freezing can occur in many of the interior areas of Northern and Central California in early November. Prepare for that possibility by moving frost-sensitive potted plants indoors or against a west or south-facing wall.

  

• Row covers, hot caps, and water-filled containers surrounding young vegetable seedlings offer these plants a warmer nighttime environment.

 

• Prepare for the rainy season by knocking down watering basins around trees.

WTF? A Freeze in February? In California? Along the Coast?

 Areas of Northern and Central California, including the coast, may see record breaking low temperatures Friday through Sunday. If your local weather forecast is calling for morning lows below 32 degrees, here's a last minute checklist:


 • If it hasn't rained, water plants thoroughly, especially container plants.
 
• If possible, move sensitive container plants next to a south or west facing wall.
 
• Cover citrus and other sensitive plants with burlap, row cover fabric or sheets (be sure to keep the sheets dry). Tent plastic sheets over the plants; don't let plastic touch plant leaves. A light bulb placed in such a plant can offer a few degrees of protection.
 
• If using an anti-transpirant polymer coating material such as Wilt-Pruf or Cloud Cover, apply at the warmest time of the day, or at least six hours before an expected frost. However, research conducted at Washington State University concluded that these products may actually be detrimental to certain plants during a freeze. If using these products, thoroughly water the soil around the plant before applying.
 
• Disconnect hoses and drip lines, removing end caps. Lay out straight.
 
• To prevent broken grass blades, don't walk on a frozen lawn.
 
• Remove the lowest sprinkler head to drain.
 
• Cover unprotected faucets and pipes, including any spa or pool equipment.
 
• If temperatures are predicted to fall to the low 20's: prevent frozen attic pipes. Let lukewarm water trickle out of the indoor faucet farthest from the inlet. Also, let faucets with pipes running along an outer, north facing wall trickle during the night. 

• Ideally, add insulation to attic water pipes.
 
• Open cabinet doors to get more heat to the pipes. Close the garage door if water pipes pass through the garage.
 
• Setting your thermostat nightly at 55 can add needed heat to the attic pipes.
 
• If leaving the house for a vacation during an expected freeze, turn off the water to the house, and open up the faucet farthest from the inlet. Be sure to turn off your water heater.
 
• To prevent cracking tile, run your pool and spa equipment during the freezing hours.

• Don't forget about your pets during a prolonged freeze. Bring them indoors at night. Move or replace their drinking water. Break up any frozen water in bird baths.

Post-Freeze Garden Tips

The average frost season for Sacramento is about two months, primarily December and January. But temperatures below 32 have been recorded as early as the first week in November; as late as the third week in March. This year, it was a Thanksgiving freeze, when temperatures plummeted into the low 20's Thursday morning, remaining there for more than 8 hours. Friday morning's lows also dipped into the 20's. And that's a recipe for definite plant damage.

 After several days of bone-chilling mornings with temperatures dipping into the low-to-mid twenties, should shivering gardeners:

a) remove all plants that look frost-bitten; 

 
b) prune away all freeze-damaged plant parts;

c) Purchase and plant again this weekend those same varieties of trees, shrubs, perennials and annuals;

                 

d) water the garden, even if the plants resemble toast;

            

e) fight the urge to prune and plant by staying indoors, next to the wood stove?

The answers happen to be the easiest to accomplish on a cold weekend: d) and e).

Even if plants in your garden look blackened and wilted now, new growth may emanate from the base of the plant when the weather warms up in a couple of months.

Pruning away the dead portions now exposes buds that may still be alive; another frosty morning could wipe out those survivors. 

Hostas will get new growth from the base.

Parsley can take a freeze. Tomatoes? No.

So, keep the shears in the garage and let the dead portions of the plants protect the understory. It may take until mid-Spring before you see new growth; patience is key before you pick up the pruners.

Make sure your garden and potted plants remain moist. Water
gives off heat, and this can protect plants from freezing, especially borderline citrus trees, such as lemons and limes. Damp soil retains heat better than dry soil, protecting roots and warming the air near the soil.

 

Other frosty garden tips that bear repeating:
• If you still have cold-susceptible potted plants on the porch or patio, move them to a sunny spot indoors or to a west or south-facing outdoor wall.

• Another way to achieve a few degrees of protection: construct a tent around a freeze-threatened plant, especially citrus, using frost blankets or row cover material. Your local nursery will have several products that will do this job. Old bed sheets work well, too.

• The larger sized Christmas lights or a couple of 150-watt light bulbs located in the central area of an orange tree (or any other cold-intolerant shrub) may add two to four degrees Fahrenheit of protection.

• Harvest any citrus fruit that is ripe, especially on the outer
branches.

• Wrap any exposed plastic water pipes; cover outdoor faucets, as well.

• Adjust your pool, spa or pond filtration timers so that they are running when the chance of freezing temperatures is greatest, between 2 and 9 a.m. Moving water is less susceptible to freezing.

• Make sure the backyard birdbath isn't frozen over in the morning.

• Daily fresh water for dogs and cats is also a good morning habit.

And what about those plants that have frozen past the point of
return? Should you replace them with the same varieties? That frozen ficus may be Mother Nature's way of telling you: "Hey! This ain't San Diego! Pick outdoor plants that can take colder temperatures!"

 

Coleus, a summer annual here: It's dead, Jim.

From the garden e-mail bag, Rob asks: "A lot of my lantana was burned by the cold weather. Should I trim in winter or wait until spring?"

Lantana is from the tropics, so it is a borderline plant here.
A light frost usually just damages the outer leaves; but a heavy frost or freeze may kill the entire plant. The good news: it may come back to life with new growth from the base, but not until late in spring. In the meantime, do nothing. Those dead branches may be keeping the base alive.

Frost/Freeze Season Approaches. Is Your Yard Ready?

 The typical Sacramento-area frost season (when temperatures dip to 32 or below for short periods of time) is fairly short: primarily, December and January.

However, November frosts do happen here with regularity. 

The earliest frost date for Sacramento was on a November 4, back in 1935, when the morning low fell to 30 degrees. The latest frost date recorded was on March 27, 1898, with a low of 32.

Last year, the first frost occurred on Nov. 17, when the  temperature at Sacramento Executive Airport dipped to 32. The last frost of the 2009-2010 season? March 19, when temps fell to 32 in Marysville and several other locations around Sacramento.

What is cold? Some definitions:

Frost: temperatures dip to 32 °F (0 °C) for short periods of time. Occurs with fair skies and light winds.

Freeze: temperatures at or below 32 °F

Hard Freeze: temperatures below 28 °F for several hours.

This morning (Oct. 27), temperatures here dipped to 38, cold enough to create frosty windshields. Which means that fruit-laden citrus trees could be threatened in the weeks ahead. Some tips for the upcoming cold mornings:


Before a frost:

• Identify cold spots in landscape by monitoring with a thermometer that registers high and low temperatures.

• Identify plants at risk: citrus, succulents, tender perennials, tropical and subtropical plants.

• Have supplies ready: sheets or frost cloths, lights, wraps for trunks, thermometers, stakes or framework to hold covers off foliage.

• Prepare tender plants: avoid fertilizing and pruning after August to minimize tender new growth. 

• Plant insurance: In September and October, take cuttings from frost sensitive perennials; keep cuttings in a sunny, indoor area.

• Rake away mulch to allow soil to warm up during the day and radiate heat at night into plant.

• Monitor weather forecasts and note how low temperatures will be and for how long. 

 

When a frost is forecast:

1. Move potted plants to a warmer spot next to house or under patio cover, especially on south side.

 2. Check that plants are well watered since dry plants are more susceptible to damage, and moist soil retains heat better than dry soil.

3. Cover plants with a row cover before sunset to capture ground heat radiating upward at night, but remove covers daily if it is sunny and above freezing to allow soil to absorb heat.

4. Add heat by using outdoor lights: hang 100 watt drop lights or Holiday string lights to interior of plant. Use the old C7 or C9 large bulbs, not new LED lights which do not give off heat.

5. Wrap trunks of tender trees if hard freeze is expected, using towels, blankets, rags, or pipe insulation.

6. Harvest ripe citrus fruit. Generally, both green and ripe fruit are damaged below 30 degrees, but there is some variation by species (refer to the chart in UC/ANR Publication 8100, "Frost Protection for Citrus and Other Subtropicals").


When a Freeze or Hard Freeze is Forecast (temperatures remain at or below 28 degrees for several hours)

  1. Wrap any exposed plastic water pipes; cover outdoor faucets, as well. Turn off the water supply to outdoor irrigation faucets, if possible. Allow those faucets to drain.

 





2. Disconnect garden hoses and lay them out straight...away from driveways!


3. Adjust your pool, spa or pond filtration timers so that they are running when the chance of freezing temperatures is greatest, between two and nine a.m. Moving water is less susceptible to freezing.

After a frost:

1. Identify damage: dark brown or black leaves and twigs.

2. Wait to prune out damage until after danger of frost is past, and new growth begins in spring.


3. Make sure the backyard birdbath isn't frozen over in the morning. Daily fresh water for dogs and cats is also a good morning habit.