JULY
2005

 

 

 

By
Beverly Shaw
 
Advanced
Master Gardener
Purdue University

 

 

 

 

 

07-07-05

Question and Answer

Q. We have a dwarf peach tree that is full of blossoms in the spring, has wonderful looking peaches, and, then, about midway through the season, all the peaches fall off just weeks before maturity. Do you know what would cause this? Also, what do you recommend for keeping shrubbery around a house green and healthy? I used to use fertilizer spikes for shrubs but have trouble locating them in stores now.

A. In mild years when most of the flowers survive, a tree may set more fruit than it is capable of supporting. The tree may then self-abort some of the fruit in a natural thinning process sometimes called "June drop." The tree will drop many small-sized (one-half to 1 inch in diameter) fruit at about the same time, making for a dramatic show. Horticulturists think competition for water and nutrients causes June drop. Peaches with the weakest seeds are usually the first to drop.

Most trees retain some fruit to carry through to maturity. It's unusual if your tree is truly dropping all of its fruit. Make sure you're providing adequate water and nutrients as the fruit matures. If all of what appears to be small fruits are falling off, it may be due to a lack of successful pollination. If there is frost damage to the pistil of the flower, the ovaries might begin to swell, and then drop off due to lack of development of the ovule into seed. Lack of bee activity could also bring the same result. If the fruit are staying on long enough to size up but are dropping before they ripen, it may be either a disease, such as scab, or some type of insect, such as stink bug or curculio. Since the possibilities are numerous, pay close attention this year, and see if you can narrow down the options.

Water, fertilizer and your attention will keep shrubs green and healthy. A weekly trip through the garden, with an eye for discolored or damaged foliage, will help you find nutrient deficiencies, insects and diseases before they get out of hand.

I prefer to fertilize with an annual application of llama manure from a nearby farm and add a granular or liquid inorganic fertilizer as needed during the growing season. Your own preferences depend primarily on soil test results. Then you have many options.

Organic sources are slower in releasing nutrients because they must be decomposed by soil microorganisms before they are available to plants. Synthetic organic fertilizers have been developed for their slow release characteristics, reducing the possibility of fertilizer injury to plant roots. The principal advantage of natural organic fertilizers is that they improve soiltilth, or structure, while meeting the nitrogen requirement of plants, if supplied in sufficient amounts. For example, manures incorporated in surface soils reduce crusting and enhance seedling emergence. Animal manures, however, may create a problem by introducing weed seeds into the area.

When nutrients are the primary interest, inorganic fertilizers are often favored. They cost less per unit of nutrient, contain greater percentages of a given nutrient and are easier to handle and apply because they are more concentrated and less bulky. The nutrients are more quickly available to the plants and are not dependent on the rate of organic decomposition, which, in turn, is dependent on temperature, moisture and soil composition.

Since nitrogen moves through the soil readily, surface application is suitable if only nitrogen is being applied. If soil tests indicate a need for either phosphorus or potassium, placing the nutrients in holes in the root zone of the trees is preferred. Fertilizer in holes 1 or 2 inches in diameter and 12 inches deep will reach many of the feeder roots of trees. Feeder roots of most trees are abundant in the top foot of soil. Holes may be punched in the soil with a steel bar or drilled with an auger attached to an electric drill. The latter method is preferred in heavy soils, since it does not compact the sides of the holes and permits dissolved fertilizer to move more freely from the hole. Such drilling has the added bonus of improving aeration in heavy soils. When the added fertilizer is combined with organic matter backfill, the hole drilling and filling process is known as "vertical mulching."

Space holes 2 feet apart in a rectangular pattern beneath and somewhat beyond the spread of the branches. Do not drill holes within 2 feet of the trunk of trees with a 12-inch trunk diameter or within 3 feet of trees with an 18-inch diameter. The required amount of fertilizer, based on the area to be covered and rate of application, should be divided equally to fill the number of holes and can be applied with a funnel or a can with the top edge bent to form a pouring spout. After the fertilizer has been added, water thoroughly. The holes then can be filled with sand, topsoil or organic matter. 

So-called "food spikes" that are driven into the ground at intervals beneath and around trees and shrubs may be used as an alternative to drilling and filling holes, but they are more expensive than the method described above. I have seen fertilizer spikes in garden, hardware and mass merchandise stores. Keep shopping! I'm sure you'll find them.

Whichever method you choose, make sure you follow label directions. Over-fertilization can kill plants. For more information, contact the Purdue Extension office in your county and ask for "Fertilizing Woody Plants," HO-140-W, or find it online at http://www.hort.purdue.edu/ext/HO-140.pdf

Q. My concern is about dead-looking clematis vines. I have more than two different types of vines that grow together. One will sprout leaves on the previous growth the following season while the other startsregrowth from the ground. How can I tell the difference when pruning in the spring or fall? Your answer would be appreciated. Thank you. -- Pat O'Connor, Wheatfield, Ind.

A. There are two major types of clematis. First, there are clematis that flower on last year's growth in spring and early summer. Examples include:

BarbaraDibley
Crimson King*
Duchess of Edinburgh
The President
*Also flowers on current season's growth if pruned in spring

Plants in this group can have either large, individual blooms or numerous clusters of small flowers. Because the flower buds are produced in the previous year, these plants should only be pruned immediately after flowering. Pruning in fall or winter removes the flower buds, thus removing the potential for bloom. In fact, plants in this first group do not require annual pruning and may actually flower better if leftunpruned for several years. If plants are badly overgrown and are in need of renovation, a severe, late-winter/early spring pruning may help rejuvenate the vine, but keep in mind that blooming that year will be sacrificed.

The second type is clematis that flower on the current season's growth in late summer and early autumn. Examples include:

Comtesse deBouchaud
Earnest Markham
Gipsy Queen
Hagley Hybrid
Jackmanii
Lady Betty Balfour
Nelly Moser*
Niobe
Ramona*
Ville de Lyon
William Kennett
*Also flowers on last season's growth if old growth is allowed to remain.)

Plants in this group have a tendency to become bare at the bottom of the vine unless pruned annually in late winter. Cut these plants back nearly to the ground, leaving at least one pair of healthy looking buds on the trunk.

Clematis actually display several more types of growth habits other than just these two simple categories. For the serious clematis enthusiast, a trip to the library or bookstore is highly recommended, so pruning technique can be customized to the individual cultivar. In addition, here are some online information sources on clematis pruning:

The International Clematis Society http://ds.dial.pipex.com/clematis/prune.htm
Pennell's Clematis Nursery (U.K.) http://www.pennells.co.uk/
Growing Clematis http://ohioline.osu.edu/hyg-fact/1000/1247.html

I have inherited some clematis whose cultivar names are unknown to me. I handle that by waiting until the plants begin to leaf out in spring before pruning. Then I remove only dead wood. Clematis stems are easy to break so prune with care.

Q. Our amaryllis are through blooming for this year. How is the best way to keep them until next winter? -- Clyde Dawson, Urbana, Ind.

A. After the flower fades, cut the flower stalk off. Water and fertilize as you would other houseplants, and place near a sunny window.

Now that all danger of frost is past, you can plunge the pot into the soil outdoors in an east- or west-facing location. Late in summer, as the leaves begin to yellow, gradually cut back on watering until the leaves fade completely, and the soil is dry.

Dig the pot out of the ground and bring it back indoors. The bulb is now dormant and should be left in the pot and stored in a cool, dark location at about 40-55 F. Amaryllis do not require as much of a chilling period as do many other flowering bulbs, but they do require a period of cool, dry dormancy. After about two months of rest, water the soil and set the pot in a sunny window, and resume normal care.

 

Contact: B. Rosie Lerner
Editor: Olivia Maddox,