Discolored berries are another example of crops affected by intense summer heat
This close-up on two blackberries shows the white-to-tan drupelets that can develop in hot, dry weather. Courtesy UC Integrated Pest Management
Add another crop to our list of heat victims this summer: Blackberries.
Throughout the Sacramento region, blackberries are developing odd white or tan discoloration. The little drupelets – the juicy sacs that make up the berry – turn white or tan. It’s not just cosmetic; they generally don’t taste so good either. Often, the discolored drupelet withers to nothing but a dried seed.
I noticed these weird drupelets on my own Baby Cakes blackberries as well as the wild blackberries that grow near our home. Was it the heat?
Thanks to Farmer Fred Hoffman (and UC research), we know why: Excess UV radiation. (And yes, that’s related to the heat.)
Hoffman, host of “Garden Basics with Farmer Fred” podcast, solved this mystery in response to an Oroville listener who saw her berries go from pink to tan to yuck.
In his column, Hoffman recapped heat-related problems with other crops such as tomatoes.
“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 because of extended heatwaves. The problem is known as White Drupelet Disorder (WDD),” Hoffman wrote.
It’s not just a matter of adding shade; the berry plants need humidity.
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. ...
“While white drupelets may seem to be directly caused by weather, they are actually caused by ultra-violet (UV) radiation,” note the UC experts. “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.”
How do you combat WDD? Make your own fog.
“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,” say the researchers. “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.”
Learn more here: https://ipm.ucanr.edu/agriculture/caneberries/white-drupelet/#gsc.tab=0
Hoffman also cited other university researchers. As other berry-growing regions get hotter and drier, WDD will only become a bigger problem.
Meanwhile, Hoffman offered tips for berry success in his “Beyond the Garden Basics” segment, plus reasons why taking time to smell the roses (and other aromatic plants) really is good for you in his Friday podcast, “Stressed? Your Garden Can Help.” (And who isn't this summer?)
Find Hoffman’s podcasts and more here: https://gardenbasics.net/.
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Flowers in My Back Yard Series
Aug. 25: Crape myrtles, Sacramento's unofficial tree of summer
Aug. 18: Pollinators adore scabiosa, aka pincushion flower
Aug. 11: Hardy hibiscus adds big tropical impact
Aug. 4: Dianthus a deceptively hardy flower
July 28: Naked Ladies put on summer show
July 21: Thank Luther Burbank for these long-lasting beauties (Shasta daisies)
July 14: How to keep hydrangeas happy
July 7: Grow these bright cosmos for bees and butterflies
June 30: Agapanthus adds blue fireworks to the garden
June 23: Easy-care gazanias fill those hot corners
June 16: Daylilies are perfect for water-wise gardens (and a lot more)
June 9: Grow coneflowers for pollinators -- and yourself
June 2: Sunflowers capture Sacramento's summer attitude
May 29: Are your roses going 'blind'?
May 26: Zinnias are the summer flowers every garden needs
May 19: Plant dahlias now for late-summer flower power
May 12: Know your coreopsis from your bidens
May 5: Mums the word on Mother's Day weekend
April 28: Majestic Matilija poppy is worth a look
April 21: Celebrate roses, America's favorite flower
April 14: Small flowers with outsized impact
April 7: Calendulas do double duty
April 3: Make Easter lilies last for years to come
March 31: In praise of a pollinator magnet (small-leaf salvias)
March 24: Azaleas brighten shady spots
March 17: The perfect flower for beginners? Try zonal geraniums
March 10: Keep camellias happy for years to come
March 3: Fruit tree blossoms are a fleeting joy
Feb. 27: Are your roses looking rusty?
Feb. 24: Treasure spring daffodils now and for years to come
Feb. 17: How and why to grow wildflowers
Feb. 10: Let's talk Valentine's Day roses
Feb. 3: Why grow flowers?
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Garden checklist for week of Aug. 16
During this break in the heat, feed your garden. Make sure to water before and after applying fertilizer.
* In the garden, direct seed beets, carrots, leaf lettuce and turnips.
* Plant potatoes.
* Harvest tomatoes, beans, squash, pepper and eggplants to prompt plants to keep producing. Give your plants a deep watering twice a week, more if planted in containers. Also, give them a boost with phosphate-rich fertilizer to help fruiting.
* Watch out for caterpillars and hornworms in the vegetable garden. They can strip a plant bare in one day. Pick them off plants by hand in early morning or late afternoon.
* Feed citrus trees their last round of fertilizer for the year. This will give a boost to the fruit that’s still small.
* Mulch can be your garden’s best friend – it conserves moisture while blocking out weeds. But don't let mulch mound around stalks, stems or trunks. That can promote rot.
* Camellia leaves looking a little yellow? Give them some chelated iron. That goes for azaleas and gardenias, too.
* Pick up after your fruit trees. Clean up debris and dropped fruit; this cuts down on insects and prevents the spread of brown rot. Then feed fruit trees with slow-release fertilizer for better production for next year.
* To prolong bloom into fall, feed begonias, fuchsias and container plants. Always water before fertilizing.
* Fertilize fall-blooming perennials, too. Chrysanthemums can be fed until the buds start to open.
* Prepare for a fall full of flowers by paying a little extra attention to your garden. Cut off spent blooms from roses, annuals and perennials, then give them a boost of fertilizer. Make sure to water plants before feeding. Roses will rebloom about six to eight weeks after deadheading.
* Indoors, start seedlings for fall vegetable planting, including bunching onion, cabbage, broccoli, cauliflower, kale, radicchio and lettuce.
* Sow seeds of perennials in pots for fall planting including yarrow, coneflower and salvia.
Contact Us
Send us a gardening question, a post suggestion or information about an upcoming event. sacdigsgardening@gmail.com
Food in My Back Yard (FIMBY) Series
Lessons learned during a year of edible gardening
WINTER
Is edible gardening possible indoors?
Hints for choosing tomato seeds
Why winter is the perfect time to plant fruit trees
When to plant? Consider staggering your transplants
How to squeeze more food into less space
Plant a fruit tree now -- for later
Win the weed war by tackling them in winter
Tips for planting bare-root trees, shrubs and vegetables
Time to give vegetable seedlings some more space
Ways to win the fight against weeds
FALL
Add asparagus to your edible garden
Soggy soil and what to do about it
Plant artichokes now; enjoy for years to come
It's late November, and your peach tree needs spraying
What to do with all those fallen leaves?
Prepare now for colder weather in the edible garden
Plant a pea patch for you and your garden
As citrus season begins, advice for backyard growers
We don't talk (enough) about beets
Seeds or transplants for cool-season veggies?
How to prolong the fall tomato harvest
SUMMER
How to get the most out of your pumpkin patch
Summer-to-fall transition time for evaluation, planning
To pick or not to pick those tomatoes?
Enhance your food with edible flowers
Why won't my tomatoes turn red?
A squash plant has mosaic virus, and it's not pretty
Tear out that sad plant or baby it? Midsummer decisions
How to grow summer salad greens
Weird stuff that's perfectly normal
SPRING
Help pollinators help your garden
Battling early-season tomato pests
Where are the bees when you need them?
How to help tomatoes thrive on hot days
Your plants can tell you more than any calendar can
Maintain soil moisture with mulch for garden success
What's (already) wrong with my tomato plants?
Should you stock up on fertilizer? (Yes!)
Grow culinary herbs in containers
When to plant summer vegetables
Don't be fooled by these garden myths
Fertilizer tips: How to 'feed' your vegetables for healthy growth
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