Extended exposure to moisture leads to blemished skin, fruit drop
These lemons show how tule fog can damage fruit. The unblemished lemon grew on the interior of the tree, the "freckled" one on the outside, exposed to the persistent fog. Debbie Arrington
Like most Sacramentans, I’ve had my fill of tule fog – and so has my citrus trees.
I discovered, as did other citrus growers, that too much fog can damage lemons, grapefruit, oranges, kumquats and other citrus. And this winter, we’ve definitely had “too much” tule fog.
Tule fog is the regional name for dense ground-hugging radiation fog. One of the most persistent kinds of fog, tule fog is named for the valley’s marsh grasses and can reduce visibility to zero. On calm, clear nights, the ground radiates heat. Water vapor near the surface condenses into fog. Without wind to move it around, this thick fog stays put – often days at a time.
Starting Nov. 21, Sacramento saw a streak of gloomy, foggy days that stretched more than three weeks – just when citrus was ripening. Temperatures during that record fog immersion also stayed chilly, rarely moving out of the 40s.
This week, that tule fog returned, along with the same issues.
Tule fog keeps everything moist, and that’s the problem. That constant exposure to chilly moisture bursts the skin cells on citrus fruit, causing blemishes. The damage can look a lot like frost exposure.
“Extended, heavy fog (such as tule fog) causes significant cosmetic damage, rind blemishes and fruit drop in citrus by keeping fruit constantly moist, leading to cell rupture,” say the UC master gardeners. “This, combined with cold temperatures, results in surface staining (black or brown spots), and increased susceptibility to fungal diseases such as anthracnose, which causes dark staining and rot.”
My grapefruit look like they’ve got the measles (or lots of unwanted freckles) with little brown spots pockmarking their yellow skin. (Fortunately, these blemishes don’t affect their juice.)
Usually, I “store” my Meyer lemons on the tree, letting nature take care of them until they’re needed in the kitchen. But this winter, the lemons growing on the outside of the tree – away from the trunk and more exposed to the fog – look like they’re beat up, with little brown scars and pitted blemishes. Several lemons just fell off.
Thankfully, the lemons growing in the interior of the tree’s canopy got some fog protection and look normal.
Tule fog can lead to citrus fruit drop, say the master gardeners. Citrus growers can lose 15% to 20% of their harvest due to prolonged tule fog exposure.
The solution? Pick citrus (especially if prolonged tule fog is in the forecast), dry the fruit well and store in the refrigerator.
And hope for some sunny, dry, fog-free days.
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Garden checklist for week of Aug. 2
Get out early in the morning and monitor your garden’s moisture needs. Deep water and add temporary shade structures for plants that are feeling a little burned. In particular, protect developing peppers and eggplant.
* Put off fertilization until this heat passes; plants need to concentrate on hydration instead of growth.
* 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.
* 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.
* 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.
* Pinch off dead flowers from perennials and annuals to lengthen their summer bloom.
* Pick up after your fruit trees. Clean up debris and dropped fruit; this cuts down on insects and prevents the spread of brown rot.
* 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. 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.
* In the garden, direct seed beets, carrots, leaf lettuce and turnips. Make sure to keep seeds and seedlings consistently moist.
* Plant potatoes.
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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
Dec. 16: Add asparagus to your edible garden
Dec. 9: Soggy soil and what to do about it
Dec. 2: Plant artichokes now; enjoy for years to come
Nov. 25: It's late November, and your peach tree needs spraying
Nov. 18: What to do with all those fallen leaves?
Nov. 11: Prepare now for colder weather in the edible garden
Nov. 4: Plant a pea patch for you and your garden
Oct. 27: As citrus season begins, advice for backyard growers
Oct. 20: Change is in the autumn air
Oct. 13: We don't talk (enough) about beets
Oct. 6: Fava beans do double duty
Sept. 30: Seeds or transplants for cool-season veggies?
Sept. 23: How to prolong the fall tomato harvest
SUMMER
Sept. 16: Time to shut it down?
Sept. 9: How to get the most out of your pumpkin patch
Sept. 2: Summer-to-fall transition time for evaluation, planning
Aug. 26: To pick or not to pick those tomatoes?
Aug. 19: Put worms to work for you
Aug. 12: Grow food while saving water
Aug. 5: Enhance your food with edible flowers
July 29: Why won't my tomatoes turn red?
July 22: A squash plant has mosaic virus, and it's not pretty
July 15: Does this plant need water?
July 8: Tear out that sad plant or baby it? Midsummer decisions
July 1: How to grow summer salad greens
June 24: Weird stuff that's perfectly normal
SPRING
June 17: Help pollinators help your garden
June 10: Battling early-season tomato pests
June 3: Make your own compost
May 27: Where are the bees when you need them?
May 20: How to help tomatoes thrive on hot days
May 13: Your plants can tell you more than any calendar can
May 6: Maintain soil moisture with mulch for garden success
April 29: What's (already) wrong with my tomato plants?
April 22: Should you stock up on fertilizer? (Yes!)
April 15: Grow culinary herbs in containers
April 8: When to plant summer vegetables
April 1: Don't be fooled by these garden myths
March 25: Fertilizer tips: How to 'feed' your vegetables for healthy growth
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