Sunday, July 26, 2015 1 comments By: Ask A Master Gardener

Watering Newly Planted trees Until Establishment

Newly planted trees need supplemental watering to get established
Lisa Klein: Ask a Master Gardener
July 26, 2015 12:00 am

Q: I planted some maples recently and am unsure as to how much water they need and how long I should be watering them. Suggestions? Roland, Tulsa

A: Supplemental watering is often neglected after planting a tree, which is one of the major causes of loss of young trees along with incorrect planting.
At a recent OSU horticultural conference, urban forester Chris Martin suggested a scientific approach to irrigation of newly planted trees. He stressed that these recommendations should be modified according to temperatures and the amount of rainfall.
For best establishment and in the absence of rain, a newly planted tree should be shallowly watered daily for two weeks and then should be watered deeply three times weekly. As to how long to water, he suggested seven months of watering three times per week for each inch of trunk diameter. So if a tree is 2 inches in diameter, water three times a week for 14 months. This is about the amount of time it takes for most newly planted trees to grow enough roots to be considered established.
Newly established trees and mature trees need to be watered deeply once per week, depending on the amount of rainfall. The recommendation for the amount of water to be applied to newly planted trees at each irrigation is also based on tree size. These trees should receive 5 gallons of water per inch of trunk diameter at each application. A tree 2 inches in diameter should receive 10 gallons of water at each watering. To be more accurate, he also suggested using a soil moisture probe to determine when and if the tree needs water. In the absence of a probe, consider using the above formulas.
Other recommendations for young tree care include tree wraps and mulch. Tree wraps should be applied to the trunks of thin-barked trees such as maples in October and removed in March. These crinkled Kraft paper wraps are widely available in garden centers. Wraps prevent freezing and thawing damage to newly planted tree trunks. This is the major cause of split bark and large open gaps in trunks of young maple and other trees. This damage definitely shortens their life span. These wraps are not needed in summer and may be harmful by providing a home to damaging insects and disease.
All trees should be mulched after planting. Two to 4 inches of a loose mulch will conserve water, moderate ground temperatures and keep out weeds and lawn equipment. Keep the mulch a few inches away from the trunk. If piled up on the trunk, it promotes disease and pest problems. It has been shown that all trees mulched after planting grow much faster than unmulched ones.
For more information about tree care, go to and review tree planting and care information under “Lawn and Garden Help.”

Garden tips
Garden tips
Spider mites are a difficult pest to deal with. They love hot, dry and dusty weather. Tomatoes are a favorite target where they cause a stippling or sand-blasted appearance. They are very small but may be seen if you tap a leaf over a sheet of white paper and look for moving dots. Treat with jets of water to wash them off and use either horticultural soap or oil according to directions. Neem oil is a good choice for a safe organic insecticide. If you use an insecticide of any sort, it is best to spray very early or late in the day when honeybees are in their hive.

Tomato growers are aware that fruit production usually stops in the heat of summer. Most tomato pollen becomes infertile and blossoms drop off when night temperatures are above 70 degrees and daytime is above 92 degrees for a few days. This also occurs in peppers, some varieties of beans and other vegetables. As it cools in late summer, fertility returns. If your tomatoes are too tall and gangly, you may cut them back a third. New growth and fertile blossoms will develop when it cools in fall.

Saturday, July 11, 2015 0 comments By: Ask A Master Gardener

Tomato Fruit Problems--Blossom End Rot

Root-top growth imbalance in tomatoes can cause rot

Brian Jervis:  Ask a Master Gardener

Saturday, July 11, 2015

Q: Some of my tomatoes are rotting. I keep them off the ground, but they still have rot. What should I do? T. S., Tulsa

A: Tomato fruit splits, rots or develops blemishes for several reasons. Usually the causes are not due to insects but to infections or, more likely, related to growing conditions. Your tomatoes may have a condition called blossom end rot.

Tomato health is dependent on the balance of root function and the plants’ top growth. In some situations, tomato plants will not have enough roots to supply water and nutrients to the rapidly growing top part of the plant. In this situation, water and nutrients, including calcium, are directed to the plants’ leaves rather than the fruits. The energy-producing leaves are more important for survival than fruits.

Even though soils may have ample amounts of calcium (and our soils usually do), the redirection of sap into leaves, rather than fruits, causes a calcium deficiency in the developing fruits. In areas of the fruit that have a lack of calcium, the tissue dies. Because the part of the fruit farthest from the stem develops calcium deficiency first, that is where the fruit is damaged. This is where the blossom once was, so therefore it is called blossom end rot.

This imbalance of roots to plant-top growth is seen more often early in the growing season and also occurs after deep hoeing has damaged roots. Another cause is applying too much fertilizer, especially ammonium fertilizer, which may stimulate top growth of the plant to the extent imbalance develops.

To prevent the problem, tomatoes should be mulched and have consistent watering. Fortunately, this problem is usually self-correcting as the season progresses and root growth catches up with the top growth.

Other fruit problems are splitting, sunscald and fungal infections. Fruit splitting occurs in plants that have gone from too little to too much circulating water. Tomato skin growth cannot contain the surge of water coming into the fruit, and the skin splits.

Sunscald occurs later in the summer. The hot sun may cause sunburn of the tomato skin, and large blisters usually develop in a sun-exposed area. These may become secondarily infected and rot. Sunscald can occur when too many leaves have been removed from the plant. The use of cheesecloth to shade the tomatoes is a workable solution.

Tomato fruit infections often come from fungi and bacteria in the soil. A good layer of mulch along with careful watering will help prevent splashing from soil to tomato fruits.

More detailed information can be had from four Oklahoma State University fact sheets about growing tomatoes and the various problems related to disease, insects and growing conditions. These are available at in the Lawn and Garden section under vegetable information.

Garden tips
When watering your lawn, ornamentals or vegetables, always do so in the morning if possible. If watered in the evening, plants will go into the night still being moist. Most disease-causing organisms need moisture, and because they grow best at night, leaving leaves wet in the evening will promote many plant diseases.

Bulb onions are ready to harvest when the tops fall over. They should be removed and allowed to dry in a well-ventilated, shaded area. After the tops are completely dry, they may be stored in a cool, dry area.

Tall, spindly tomato plants with scarce fruit are usually due to either too much nitrogen fertilizer or too much shade

Saturday, July 4, 2015 0 comments By: Ask A Master Gardener

Azalea Root Disease

Root rot can turn beautiful azalea bush into a corpse

Bill Sevier: Ask a Master Gardener  

Saturday, July 4, 2015

Q: I have five azalea bushes next to my house that are dying. They have been losing whole limbs over time, and now most all the plants are dead. The leaves are a bit yellow, but I don’t see any insects. They get plenty of water and afternoon shade. What could this be? J.T., Tulsa.

A: Generally azaleas do pretty well in our area other than some nutritional problems related to soil acidity and infestations with an insect called lacebugs.

However, these conditions will not cause an azalea to go into a death spiral as yours has. When one sees all of a shrub die with no obvious cause, this points to a problem in the plant’s root zone.
There are two main groups of pests that can involve azalea roots leading to dwindling and eventual death. One is a microscopic worm called a nematode, and the other is a root fungus.

Thousands of varieties of nematodes are normally found in the soil, but one variety called the stunt nematode can, as the name suggests, stunt and then kill an azalea. There is no treatment for this.
Far more likely cause is an infection with phytophthora root rot, the most common root fungus of azaleas. This fungus is widespread, infects many different shrubs and trees, and once established is not treatable by the homeowner. The disease may develop slowly, showing smaller yellowish leaves and shortened twigs, which leads to death of individual limbs and then death of the entire plant.

One major factor leading to the disease is overly wet soil, such as areas around the downspout of roof guttering. The disease is also more common in poorly draining heavy clay soils. Planting azaleas too deeply — deeper than the soil line it had in the nursery — causes the plants to be more susceptible to the disease. Genetics also comes into play, and some azaleas are just naturally more susceptible to root rot fungus.

As mentioned, there is no treatment for this; once the diagnosis has been made, the plant should be dug up and sent off in the trash (do not compost as the roots are infectious).

Prevention is key in the management of this disease. One should not replant an azalea in an area previously known to be infected — the fungus is still in the soil. Also, do not plant an azalea in an area where any other plant such as camellia, dogwood, yew, juniper and others have died of root rot.

When selecting a new azalea, inquire about its phytophthora root rot resistance and go for the most resistant ones. Also, plant in an area that drains well; if you have clay soil, plant your azaleas in raised beds.

Garden tips

For all your plants, ornamental or vegetable, mulching and correct watering are keys to surviving the heat of the summer. Mulch conserves water and reduces ground temperature.

Fescue lawns need 2 inches of water per week to survive summer; Bermuda grass needs about half that amount. Watering less frequently and more deeply is better than daily shallow watering.

Brown patch disease of fescue lawns is appearing now, related to excessive rains, heat and high humidity. Wet grass leaves promote the disease. Therefore, if you water in the mornings, allowing the leaves to dry during the day, there will be less likelihood of infections. Fungicides are available, but OSU feels the fungicides available to homeowners are not nearly as effective as those available to professional licensed applicators. None of these chemicals will cure existing infections; they only prevent new disease at best.