University of Vermont
Department of Plant and Soil Science

Summer News Article
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PREVENTING MILDEW OTHER JULY GARDENING TIPS

Leonard Perry, UVM Horticulturist
and Charlie Nardozzi, Garden Consultant

Preventing powdery mildew, renovating strawberry beds, and protecting blueberries from birds, are some of the gardening activities for this month.

At the first sign of powdery mildew on phlox, bee balm, and other susceptible plants, treat with Serenade or other labeled fungicide, such as one with potassium bicarbonate (relative of baking soda).  Spray plants every two weeks, or according to label directions if different, thoroughly wetting the foliage.

Now's the time when strawberry beds can become a mass of baby plants.  Renovate the beds, controlling the runners, encouraging them to root where you want them. Keep the bed well mulched and watered.
   
Birds love blueberries as much as we do, so protect the fruit with netting.   Use stakes to suspend the netting over the shrub so birds won’t reach the berries. Secure the netting to the ground to prevent birds from sneaking in. Get your cover in place before the berries turn ripe.
   
Take just one-half hour every day to inspect the garden and pull weeds. Weeds really do sprout overnight and by next week they'll be towering over your tomatoes and annual flowers.  A visit to the garden before work, or as soon as you get home, can keep the weeds in check.

Continue planting vegetables such as radishes, carrots, and lettuce so that you'll have a continual supply of these vegetables into the fall. Seeds will germinate quickly in warm soils, but so will the weeds. Be diligent about weeding, watering, and thinning your new seedlings.

Check tomato plants for large, green-striped horned caterpillars. A few can cause lots of damage, so hand pick and destroy them when found. Spray an organic pesticide containing B.t. (Bacillus thuringiensis) to control large infestations.  If the caterpillars have white elongated eggs on their backs, leave them and don’t spray.  These are a natural enemy, such as from a parasitic wasp, which hatch and then parasitize other hornworms.

Protect your squash vines from the squash vine borer.  These clear-winged moths lay their eggs on the stems and the hatching larvae bore into the vines, causing the plant to wilt and possibly die.  Apply a pesticide containing B.t. every 3 or 4 days during July and early August to kill hatching larvae before they enter the stems.  A thin layer of wood ashes or moth flakes scattered around plants may discourage egg laying.

If these don’t work on the squash vine borer, slit the vine stem where it is wilting and along it until you find the feeding grub.  Remove and destroy the grub, then bury the end of the vine so that hopefully it will root and resume growth.

Summer is a great time to visit perennial nurseries to see what is in bloom, and add to your collection.  There are many local specialists you can find online under Vermont Perennial Display gardens  (pss.uvm.edu/ppp/vpdgli.html).  As virtually all plants you’ll find are in pots, it is fine to plant them now, just add some compost at planting, mulch, and keep them watered. 
   
Other gardening activities for this month include visiting open garden days, removing “sucker” shoots from tomatoes, finishing pruning of woody plants early in the month so any new growth will have a chance to harden-off before winter, and replacing hummingbird solution in feeders and water in bird baths every three to five days.

(Charlie Nardozzi is a nationally known horticulturist, author, gardening consultant, and garden coach; gardeningwithcharlie.com).

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