Don't Water a Tree's Trunk

As gardeners, we usually don't think twice if sprinkler water is hitting a tree trunk. As long as the grass, flowers and shrubs that we want irrigated are getting water, who cares? Arborists care.

Analisa Stewart, consulting arborist for Sacramento-based Arbor Entities, cringes at the thought of what might happen to the long-term health of that tree with the trunk that's getting doused several times a week.
"Trunks don’t absorb water," explains Stewart. "Water on tree trunks is wasted irrigation."      

"A tree's main stems were not designed to come into regular contact with water," says Stewart. "More so when the outside temperature is hot. The only time main stems should be in contact with water is when it’s raining outside."

Armillaria root rot due to drip system touching tree trunk

"Water droplets are vectors for pathogens," says Stewart, who also serves on the Tree Advisory Committee for the Sacramento Tree Foundation. "The bacteria travel in water droplets. The same is true for many fungi, like anthracnose."

Water dripping off main stems to the ground aren’t readily used by trees either. "Most water-absorbing roots are at the end of the roots, farther outside the canopy," she says.

 Avoiding tree trunks with an automatic garden watering system, such as in-ground sprinklers on a timer, may be difficult. Try to adjust the sprinkler spray to that tree trunks are spared.
  

However, if you are watering a tree with a hose-end sprinkler or drip sprayers, position them to point away from the tree, not towards it.

Two Mini-Sprayers at the edge of the tree canopy, spraying outward.

 Place the sprinkler away from the trunk, at least halfway between the trunk and the dripline (outer canopy) of the tree. As Stewart says, the tree's dripline and beyond is where the water will be absorbed by the tree roots.
 
Stewart goes on: "There is some controversy about how pathogens gain access. The late Dr. Alex Shigo (the father of modern arboriculture) researched extensively and put forth the idea that pathogens could only gain access through a wound, be it a pruning cut or mechanical damage caused by rodents. Wounds were the entry point. Since his death there has been extensive research on both Pseudomonas and Phythopthora (especially P. ramorum, aka Sudden Oak Death) and early results seem to indicate that pathogens could be gaining access through lenticels, which are small openings in bark.
 
"Depending on the force of the spray, tree species, and overall health of the specimen I routinely see trees that have actually been bruised by water from sprinklers on thin barked trees. Often this leads to the formation of a canker, or sunken depressed area of bark. That area loses vascular flow and  becomes a site for other potential problems. Best case scenario is the tree has to expend resources sealing the wound, meaning those resources aren’t available for say, growth, anchorage, storage or other kinds of defense. I’m thinking specifically of a private country club that had a number of Japanese Maples all in a row, all beat to death by their irrigation system." 

Stewart concedes: "I don’t know how much a homeowner cares about all this, but she does care about my ability to manage the pathogen in the landscape."

And successful management may begin by just redirecting the water away from the tree trunk.

Now's the Time to Start the Winter Vegetable Garden

Do you want your family to eat healthy year-round? The healthiest, freshest foods are the fruits and vegetables you grow yourself. And in many areas of the West and South, the 365-day vegetable garden is easy to achieve. And now, summer, is the time to be planting the seeds and transplants for the vegetables your family will enjoy throughout the fall, winter and following spring.

Although we are still in mid-summer, this is the time to start your winter vegetable garden here in Northern California, as well as other mild-winter areas around the state and the nation. Most of this  planting can be done during the milder months of September and October (along with mid-August for some winter crops). For specific crop planting times for the various areas of California, refer to the UC Davis Vegetable Research and Information Center.

The winter garden bed should have many of the same characteristics as the summer garden: 

a sunny and level location close to the house;

a convenient water source; 

and, soil that drains easily. 

     Because of possible heavy rains in winter, raised beds can solve that drainage problem for homeowners living with clay soil. Mix in other soil amendments, such as compost and manure, to improve crop production in the foggy, wet, cold days that await.

     For foothill gardeners, a raised bed with wooden sides has an added benefit. Those structures can support a hinged, translucent top, such as glass, polyethelene or fiberglass…an instant cold frame to protect winter vegetables from low temperatures or heavy wind and rain.

     Starting vegetables in the heat of the summer, especially from seed, requires a consistently moist seedbed until the plants are up and growing. An automatic garden watering system, such as a battery operated timer that attaches to a faucet, can ease that process.

      Here are some of the winter vegetable varieties that do well in Northern California, how much room to leave between the plants in each row, and how much to plant for a family of four (with moderate appetites):

Artichokes: A bit of a challenge in the interior valleys. Easy to grow in coastal areas. Plant from roots, not seed. Green Globe; 4 feet apart; 5-10 plants.

Broccoli: Green Goliath, Green Duke, Waltham 29; 10 inches apart; 20 foot row.

Brussels sprouts: Jade Cross Hybrid; 24 inches apart; 20 foot row.

Cabbage: Earliana, Copenhagen Market, Savoy King, Burpee Hybrid; 24 inches apart;15 plants. 

Cauliflower: Snowcrown, Snowball Y, Purple Head; 24 inches apart; 15 plants.

Carrots: Nantes or Danvers half long, Short n' Sweet; 2 inches apart; 25 foot row.

Chinese cabbage: Michili, Pak Choi; 6 inches apart; 10 foot row.

Garlic: California Late, California Early, Elephant Garlic; 6 inches apart; 20 foot row.

Kale: Dwarf Blue Curled Vates, Dwarf Curled Scotch; 10 inches apart; 12 plants.

Kohlrabi: Early White Vienna, Sweet Vienna;  3 inches apart; 10 foot row.

Loose leaf lettuce: Ruby, Bibb, Salad Bowl, Green Ice;  6 inches apart; 15 foot row.

Peas: Mammoth Melting Sugar, Sugar Ann, Sugar Snap. 2 inches apart; 5 foot row.

Onions: Stockton Red, Stockton Yellow, Walla Walla, Texas White; 4 inches apart; 20 foot row.

Radish: Champion, Watermelon, Crimson Giant, Cherry Belle; 5 inches apart; 20 foot row.

Rutabaga: Victoria, Valentine, Strawberry; 3 inches apart; 15 foot row.

Spinach: Melody Hybrid, America, Bloomsdale Long Standing; 6 inches apart; 15 foot row.

Turnips: Purple Top White Globe, Shogoin (greens); 2 inches apart; 10 foot row.

Perennial Vegetables that need a lot of room:

Asparagus: Mary Washington, UC72, UC157, 500w; 12 inches apart; 20 foot row.

Rhubarb: Victoria, German Wine, Crimson Cherry; 2 feet apart ; 20 foot row.