GARDEN BLOG AT COLUMBIAN.COM

You can go straight to our new garden blog by using Columbian.com/gardenblog. You can also access all previous blogs. We are adding about 3 blogs a week.

FREE DIAGNOSIS ON PEST CONTROL PROBLEMS

Part of our expanded pest control service is free diagnosis. Contact me if your plants look sick. Wherever possible we will be using organic and bio-safe methods. In some cases we will be using a new group of pesticides with an EPA rating of “reduced risk”. These products must be at least 10 times less toxic to qualify for this government rating. They are also used at much lower rates with a corresponding lower environmental impact. For example, the new broadleaf lawn weed control product “Imprelis” is a synthetic auxin growth regulator.

PRUNE RHODIES AND OTHER SPRING FLOWERING SHRUBS AFTER BLOOM

June and July are the best months to prune Spring flowering shrubs such as Rhododendron, Azalea, Andromeda, Viburnum, Camellia, Daphne, Forsythia and Lilac. Why prune now instead of waiting until later? Spring flowering shrubs first make new vegetative growth right after flowering. By mid to late summer, they are developing new flower buds for next spring. If you wait until all the flower buds are formed and then prune, you will be removing next spring’s flowers.

What about those brown and dried left over flowers? Should they be removed? It is not necessary for the health of the plant. It will improve immediate appearance. They will soon be covered by new growth.

Summer blooming shrubs such as roses and most hydrangeas produce flowers on new spring growth. They can be pruned in the fall, winter and early spring without removing any flowers.

SPRAY ROSES BEFORE THEY GET DISEASE

Rose foliage is very beautiful this time of year. It is dark green streaked with the red of fresh new growth. There are no ugly spots or discoloration. That will soon change as black spot, mildew and rust spores are deposited on those fresh new leaves. Then the black spots, yellow discoloration, powdery mildew residue and rust pustules will begin appearing. Plants will begin dropping damaged leaves.

The first thing you can do to reduce rose diseases is to remove and destroy all the old leaves. Do not compost them. If you look closely in the lower part of the plants you will see old leaves with black spots still hanging on some plants. The spots on those old leaves are producing the spores to infect the new growth.

My favorite pesticide for roses is Neem Oil. This organic compound is an extract from the Neem Tree which grows in Australia. It prevents all three of the major rose diseases mentioned above. It also kills aphids and most other insects which attack roses. It is not long lasting. It needs to be applied at least once every two weeks. Neem oil is usually only available in full service nurseries and garden stores.

There are also many other chemical fungicides available for controlling rose diseases. Most fungicides protect only uninfected leaves. Propiconazole, Myclobutanil and Tebuconazole are all systemics which will stop disease progression in already infected leaves. Propiconazole is available in Fertilome Systemic Fungicide. Myclobutanil is in Spectracide Immunex Fungicide. Tebuconazole is in Bayer All-in-One Rose and Flower Care and Bayer Disease Control for Roses, Flowers and Shrubs. Propiconizole and Myclobutanil are applied as sprays to the leaves. The Bayer products are applied to the soil and taken up into the leaves from the roots. Systemic fungicides are translocated within the plant and stop disease development in already infected leaves as well as protecting new uninfected leaves. Daconil and Chlorothalonil are also widely available and effective, but are not systemic and therefore protect only new uninfected leaves. Besides Neem Oil, other organic fungicides are lime-sulfur (calcium polysulfide) and copper sulfate. Fungicides should be applied at 2 to 3 week intervals from June through October. You may need to read labels of ingredients to find specific pesticides mentioned.

But aren’t there some rose varieties which are resistant to these diseases? Sadly there are very few. Heirloom Roses (heirloomroses.com) has developed several disease resistant varieties. The most disease resistant roses I know are the Floral Carpet varieties. These are landscape or ground cover roses which do not have flowers suitable for cutting.

PROPER MOWING HEIGHT AND FREQUENCY

Proper mowing height and frequency will go a long way toward improving lawn performance. Grass blades are the manufacturing plant of the lawn. If cut too short there is less leaf surface for food production by photosynthesis. If grass is allowed to grow 3 or 4 inches tall and then cut back to less than an inch it shocks the plants and they use a lot of energy in replacing those leaves.

Lawns should never be cut shorter than 1½ inches. No more than 1/3 of the blade should be removed at each mowing. In early June when the lawn is growing most rapidly, it may need to be mowed every 4 to 5 days. In a month or so, when growth rate slows, once every 7 days may be enough.

If you mow frequently, so that clippings are short, they will fall between the grass blades and not accumulate on top. These clippings are turned into humus by earthworms and soil micro-organisms. The amount of fertilizer in one season’s clippings is equivalent to one application of fertilizer.

If you are a golfer, you may have noticed that the fairways are usually cut at ¾ inch or less and still are healthy and thick. If you talk to the superintendent, you will find that his mowing interval is 2 to 3 days. You will also find that he applies more fertilizer, weed killer and other chemicals.

Another practice which will improve lawn health and appearance is keeping the mower blade sharp. A dull mower blade tears the leaf edges rather than cutting cleanly. The blade tips turn brown, giving an overall dull appearance to the lawn. This dullness goes away when the blade is sharpened.

One other factor which will improve lawn growth is to apply lime amendment to the lawn at least once every 3 years. Our soils and water are naturally acid. The calcium in the lime reduces the acidity and improves grass growth. It also makes iron more readily available in the soil. Iron causes grass to grow dark green.