Posts Tagged ‘tree leaves’

Between the early freeze and the recent wind, our trees lost their leaves in a hurry.  Once again, we need to clean up the mess.  But raking, bagging and sending those leaves to the landfill is not a good idea, so why not use them in your landscape where fallen foliage turns to garden gold?

 Here are a few suggestions for living with those leaves:

Mow them with a mulcher and leave them on the lawn.  Researchers, motivated to find a way to avoid raking, have found that finely chopping leaves and letting them stay on the grass will return trace nutrients to the soil.  The decomposing leaves provide food for earthworms and other soil citizens, holds moisture for grass roots, and builds soil from the top down.   Big Tooth Maple

First, make sure the leaves are dry and then, using a power lawn mower, make two passes over the leaves on the lawn to chop them into fine pieces.  Move slowly across the yard, savoring each pass as it pulverizes the leaves.  If after two swipes the leaves still have large chunks, go over them again to get tiny particles.

Though this technique sounds tantalizingly easy, it must be repeated every three days to ensure that the leaves don’t build up too thickly on the lawn before mowing.  Should you miss a round or two, choose another use for your leaves, such as mulching perennial beds. 

Oak and cottonwood leaves should be used sparingly in this manner, as they have high amounts of tannin, and take longer to decompose.  Black walnut leaves should not be left on the lawn – they contain juglone, a chemical that prevents other plants from growing.

Mulch perennials.  Leaves make an excellent blanket for protecting perennials and woody plants from the ravages of winter.  In Colorado, thawing and freezing can lift roots, but covering the soil with a four to six-inch layer of leaves will keep temperatures consistently cool.

As long as your trees aren’t diseased, pile their leaves up around your plants and let the ones that blow into the beds settle there for winter.  In spring, rake the leaves out and put them in your compost pile.

Compost them.  Rotting, dead plants are converted to an organic material that, tilled into the soil, holds water and nutrients for roots to take up.  This is a great soil amendment to have on hand in spring.

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“What’s wrong with the tree?” is a question frequently asked in our office at this time of the season.  And for the most part, the answer is:  tree scorch and symptoms of lack of winter water.   Scorch

 Winter is a tough time for folks to think of watering trees, what with all of that chilly weather and bare branches.  But roots dehydrate in dry soils and this past winter was bone dry.  Here’s the surprise for most people: the result of no winter water is seen in mid-summer, when trees struggle with scorched leaves.

 Yes, it seems counter-intuitive, but if you don’t have the roots to support a lush canopy, the leaves lose water faster than the stunted root system can replace.  This means leaves brown for seemingly no reason, and drop from the tree.

maple scorchLook for evenly discolored spots on leaves, typically from the tips inward but not always.  The discolored area have no rings, halos or fruiting bodies – if you see any of those things, you should suspect fungus or bacteria. 

On pines, the needles will brown with no rings or banding, becoming brittle and dry.  Deciduous trees may loose a bit of canopy at this time as well, in response to high heat and low water.  This is normal, but if the tree loses a lot of the canopy it’s probably under too much stress.

Other culprits besides lack of winter water are low relative humidity, wind, soil with high salt concentrations, compacted soil, new construction near the tree, and plastic weed barriers.  In short, anything that interferes with the tree getting water.  Scorch on one side

Don’t forget the effect of heat reflected from bright surfaces, especially on conifers.  Light-colored siding gets hot, particularly on south or west sides.  Symptoms become obvious following hot, dry weather in late summer.  Evergreens may have tip dieback of needles, progressing from the tree’s top downward and from outer branches inward. 

You can’t cure the tree, but you can help it be healthier next year.  Try deep watering to a depth of 12 to 18 inches once a month in summer and winter.  Organic mulch under trees helps reduce moisture loss, but avoid polyethylene plastic under mulches – use porous weed fabrics instead.   For more info, check out CSU’s leaf scorch fact sheet.

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