Crown Gall of Rose

Source(s): Randy Drinkard

Crown Gall, a disease caused by a soil borne bacterium, can severely damage rose plants. Galls begin as small swellings, usually at ground level, that slowly increase in size. Infected rose plants become stunted and very often die.

Crown Gall of Rose
Crown Gall of Rose

Tissue overgrowths or galls can be found at or just below the soil surface on the crown and on the roots of plants. Galls are irregularly rounded and rough in texture. Galls vary in size from ½ inch to several inches in diameter. Young galls are light green or white, and the tissue is soft. Advanced galls are hard and brown to black in color. Roses severely infected become stunted, producing only a few blooms.

The crown gall bacterium enters plants through wounds made by transplanting, cultivation, grafting, and pruning. Other wounds caused by insects, animals or people can serve as avenues for infection to occur. Affected plants may be stunted, produce small chlorotic leaves and may become more sensitive to environmental stresses such as winter injury. Severely infected plants decline and eventually die. Crown gall can survive in the soil for 2 to 3 years.

To control crown gall, avoid wounding susceptible plants at or near the soil line. Prune infected branches and roots well back into healthy tissue. To prevent possible spread of the disease, sterilize pruning tools between cuts with a 10 percent household bleach solution. Plant removal may be necessary when galls are extensive. Chemical treatment may be practical for valuable landscape plants. Contact your local county agent for a list of chemicals.

Resource(s): Common Landscape Diseases In Georgia

Center Publication Number: 114

Common Lawn and Garden Terms

Source(s): Randy Drinkard

Some of the most commonly-used lawn, landscaping and garden terms include:

Annual – a plant that grows, blooms, produces seed or fruit and dies in one year or less.

Biennial – a plant that grows and establishes itself the first season, then blooms, produces seed and dies the second season.

Broadcast – a product that is distributed over a large area of space.

Compost – decomposed organic matter, used to enrich the soil and improve drainage and aeration.

Contact – a product that adheres to and is localized on the surface of the leaf or stem of the plant.

Fungicide – a product that controls a fungus.

Herbicide – a product that controls plants.

Humus – the brown or black organic part of the soil that results from the decay of leaves or other organic matter.

Insecticide – a product that controls insects.

Integrated Pest Management(IPM) – multiple tactics used in a compatible manner in order to maintain pest populations below levels that cause economic or unacceptable injury without posing a hazard to humans, domestic animals or non-target life forms.

Miticide – a product that controls mites.

Non-selective herbicide – a product that controls all and any types of plants.

Organic Matter – Any material which originated as a living organism, such as compost, manure or peat moss.

Pesticide – a product that will control a pest.

Perennial – a plant that lives for more than two years, often for many years.

Postemergence – a product that controls visible weeds.

Pre-emergent – a product applied to the soil surface that inhibits weed growth.

Rodenticide – a product that controls rodents.

Selective herbicide – a product that controls only certain types of plants, eliminating non-desirable plants while maintaining desirable plants.

Systemic – a product that is absorbed through the leaves and/or roots of the plant and moves throughout the plant.

Weed – a plant out of place.

Reviewer(s): Todd Hurt, Training Coordinator, UGA Center for Urban Agriculture, The University of Georgia College of Agricultural and Environmental Sciences, June 2006.

Center Publication Number: 206

Cold Protection of Citrus in Georgia

Source(s): Randy Drinkard

An important consideration when growing any type of citrus plant in Georgia is cold protection. Young citrus plants, even the most cold hardy types, cannot withstand freezing temperatures as well as more mature, bearing trees.

Before the first freeze, trees up to four years of age should be banked with a clean soil up to a height of about 15 inches. Soil banks should be removed after the last chance of freeze in the early spring. Wrapping material with good insulating properties such as fiberglass or foam rubber also make effective protectors and may be used in lieu of soil banks. These materials should be a minimum of six inches thick and must make good contact with the soil.

When only a few plants are involved, protective covers may be used when severe freezes occur. On extremely cold nights, placement of one or two electric light bulbs beneath the cover provides good protection.

Sprinkler irrigation can also be used to protect citrus during freezes. Start applying 1/4 inch per hour when temperatures drop below freezing and continue until temperatures rise above 32 degrees F. Support weak limbs if possible to prevent breakage from ice. The ice should be clear and icicles should be present. If ice is milky white, increase the volume of water being applied.

Among the citrus types which are most easily killed by freezing temperatures are citrons, lemons and limes. Temperatures from the mid to high 20s F. will readily kill or severely damage these plants. Sweet oranges and grapefruit are somewhat more hardy and usually require temperatures in the low to mid 20s before incurring major damage to large branches. Tangerines and mandarins are quite cold hardy, usually withstanding temperatures as low as the low 20s F. before significant wood damage occurs. But among the edible types of sweet citrus, the satsuma (also called the satsuma mandarin or satsuma orange) has the greatest degree of cold hardiness. Properly hardened bearing trees will with stand temperatures as low as 20 degrees F. without appreciable wood damage.

Keep in mind the temperature ranges given above refer only to leaf or wood damage. Citrus fruits easily freeze at 26-28 degrees F. when these temperatures last for several hours. Further, a longer duration of freezing temperatures is required to freeze fruits of grapefruits as compared with sweet oranges. And tangerines and satsuma fruits are more easily frozen than either of the former.

The particular temperature at which tissue of a given plant will freeze and the degree of the damage sustained are functions of a number of factors in addition to the species and variety involved. These factors include:

  1. the freezing temperature reached
  2. the duration of the minimal temperature;
  3. how well the plant became hardened or conditioned before freezing
    temperatures occurred (the freezing point of tissue of a hardened citrus plant may be 5 to 6 degrees lower than an unhardened plant
  4. whether the plant is wet or dry (the killing temperature is 2 to 4 degrees F. lower for a dry citrus plant)
  5. age of the plant (a young plant cannot withstand as much cold as a more mature tree).

Citrus plants seem to freeze at higher temperatures in some years than others. The contributing factor seems to be the difference between air (ambient) temperature and leaf (tissue) temperature. On a windy night with clear or cloudy skies, leaf temperature will be approximately the same as air temperature. On a cold, clear night with little or no wind movement, leaf temperature may easily drop several degrees (3 to 4 degrees F.) below air temperature because of radiation heat loss. Thus, under the latter circumstances, while the minimum air temperature on a given night may have only been 25 degrees F., actual leaf temperature of the plants may have reached 21 to 22 degrees F. The critical temperature is that of the leaf or fruit and not the air temperature per se.

Resource(s): Citrus Fruits for Southern and Coastal Georgia

Care of Citrus Plants in Georgia

Source(s): Randy Drinkard

The first three years should be devoted to developing a vigorous tree with strong scaffolds. Some fruit may be borne the second year and third growing seasons, although the quality may not be too good. Trees should commence fruiting significant crops in the fourth growing season.

Continue using the same 8-8-8 fertilizer (or equivalent) for the bearing tree. Three applications per year, February, May-June and August-September, are suggested. Apply fertilizer from near the trunk to well beyond the leaf drip of the tree (on large trees this usually involves fertilizing about 4 to 6 feet beyond the leaf drip). A reasonable rate of application to maintain healthy foliage and good fruiting is about half a pound of 8-8-8 fertilizer per year of age of the tree (rates are for sandy soils; clay soils and others with greater inherent fertility would require less fertilizer). After a number of years, a fertilizer containing nitrogen and potassium or just nitrogen alone may prove adequate. A maximum of 1.5 to 3.0 pounds of actual nitrogen per tree per year should be adequate.

As trees become older, problems may be encountered with micronutrient deficiencies. An annual nutritional spray applied in the spring usually corrects these deficiencies. Prepackaged nutritional spray mixes may be purchased from garden supply dealers. These mixes should contain manganese, zinc and copper. Deficiencies of boron may be corrected with foliar sprays or soil applications. When iron deficiency symptoms develop, chelated forms should be applied to the soil.

The pH (acidity or alkalinity) of the soil in which the trees are growing should be maintained between 6.0 and 7.0 for best growth and production. Apply dolomitic limestone, agricultural limestone or basic slag as needed to prevent the pH from dropping below 6.0. Your local County Extension Agent or garden supply dealer can assist in determining if a pH adjustment is needed.

Weed control around large bearing citrus plants becomes somewhat less essential. However, it is generally beneficial to remove all weeds and lawn grass from beneath the canopy of the plant. This approach also provides a more attractive landscape design. Of particular importance is the removal of weeds and grass from the area immediately around the tree trunk. This growth tends to create ideal conditions for fungal organisms such as those causing foot rot at the base of the tree. Mulches are not essential for best tree performance but may be used. Mulching materials should not be placed within 12 inches of the trunk.

Watering of bearing citrus plants will not be necessary in some years. But adequate water should be provided as needed particularly during flowering and fruit setting in the early spring and the dry periods of mid to late summer. A slow application of water over a several-hour period is preferable to a rapid “lawn type irrigation.”

Pruning of citrus trees on an annual basis is unnecessary. Actually, the only pruning usually required is for the removal of water sprouts (suckers) and any dead, damaged or diseased limbs. Make all cuts nearly flush with the trunk or next largest branch (don’t leave stubs). Seal all cuts in excess of 1/2 inch in diameter with a safe pruning paint – those with an asphalt base are recommended. The summer period is usually an ideal time for pruning.

Citrus plants in Georgia are always subject to injury from cold weather. If trees are only slightly damaged, pruning may be done as soon as new growth indicates the extent of injury. However, regardless of the amount of injury sustained, no pruning should be done until after danger of further freezes. If trees incur major freeze damage, allow the first flush of growth to mature before pruning.

Resource(s): Citrus Fruits for Southern and Coastal Georgia

Beat the Heat this Summer

Source(s): Randy Drinkard

Are your flowers and shrubs ready for the heat this summer? If you rely on municipal water to irrigate your landscape, you may be prohibited from using it to keep your outside plants green and healthy. Start drought-proofing your landscape now so that it can survive with little to no supplemental water this summer.


First, consider what areas require the most water and think of ways you can reduce the water use. For instance, an irrigated area might be replaced with some large beds of drought-tolerant ground covers, such as spreading junipers, like ‘Blue Rug’, ‘Sargents’, ‘Prince of Wales’ or ‘Blue pacific’. Other good, drought-hardy ground covers include, liriope, Asiatic jasmine, Carolina jasmine, trumpet creeper, day lilies and creeping raspberry.

To save money when planting a large area, ask your local nurserymen about ordering liners. Liners are small, rooted cuttings that are available bare-root or in 2-inch pots. Many Georgia growers produce liner plants, and some garden centers can get them, too, if you ask.

There are also a number of excellent drought-tolerant shrubs, such as dwarf yaupon holly, Indian hawthorn, dwarf crepe myrtle, glossy abelia and ‘Miss Huff’ lantana. And don’t forget the ornamental grasses, including maiden grass, fountain grass and Japanese silver grass. Ornamental grasses are tough as nails and are unaffected by drought conditions.

Georgia flower growers are right on target with their production of drought-tolerant color plants, including sedum, verbena, Purple Heart, gaura, wave petunias, and ‘New Gold’ lantana.

Although they sometimes shut down during periods of extended drought, these plants bounce back with renewed vigor when the rains return.

You don’t have to invest a lot of money to make your landscape more drought-tolerant. Consider putting in some sweeping beds of pine straw, pine bark or shredded wood mulch in the place of irrigated landscape. Many municipalities make shredded mulch materials available now that they can no longer put yard wastes in the landfills.

Also, old newspapers can make an excellent mulch around ornamental shrubs, flowers and vegetable plants. Use a leaf rake to gently pull back your existing mulch, wet or dip newspapers in a bucket of water and then spread papers two sheets thick on the ground. Put the mulch back over the newspaper to conceal it and hold it in place. Newpapers not only help hold moisture in the soil but add organic matter as they slowly decompose.

When retrofitting your landscape with more drought-tolerant plants, the key is to get the plants established before summer heat and watering restrictions arrive. Water your plants as needed to get them established for the first six to eight weeks after planting, then turn off the tap and let Mother Nature provide the water for the remainder of the year. By gradually reducing the amount of water supplied to the landscape and garden you will be helping to reduce the plant’s reliance on supplemental watering later this summer when temperatures and drought conditions become more severe. By slowly weaning your plants from excessive moisture, their root systems will be encouraged to grow more deeply in search of water.

Resource(s): Care of Ornamental Plants in the Landscape

Center Publication Number: 92

Attracting Birds with Ornamental Plants

Source(s): Randy Drinkard

Birds can be an important aspect of our backyard environment. In many cases, the quality of our environment is perceived to be directly related to the population of birds. The bird population in your yard or neighborhood park can be increased with the proper selection and arrangement of ornamental trees and shrubs. The selection of food-producing plants can ensure the presence of birds year-round.


To attract and maintain a bird population, a habitat should provide (1) food, (2) cover, (3) nesting areas, and (4) water. Ornamental trees and shrubs can supply the necessary cover (shelter) and nesting areas. Many ornamental plants can satisfy more than one habitat requirement. For instance, multi-stem plants that form a dense canopy will satisfy the needs for nesting and also provide cover.

The food source for birds should be supplied, as much as possible, by the trees and shrubs in the yard. To maximize the natural food source, select plants to ensure an available food source year-round. The use of trees and shrubs native to your locale will help ensure that appropriate fruits and berries are available for the local bird population. If the landscape does not supply food during certain periods, you can supplement with commercial mixes of bird seed. This will help keep birds in the vicinity of your yard. Some birds eat a wide variety of seeds while others prefer one or two types. The seeds that appeal to the majority of birds are sunflower, proso millet, and peanut kernels.

Birds require a place of cover or shelter if they are to become long-term residents. They require protection from inclement weather (sun, heat, wind, and rain) and natural predators. This is why the multi-stem plants that form a dense canopy are preferred by birds. The dense canopy also provides an ideal environment for nesting. Since birds require shelter year-round, the yard should have a mix of deciduous and evergreen plants. Evergreen plants include broadleaf evergreens, such as holly, and conifers, such as red cedar. Several references suggest that at least 25% of the trees and shrubs should be evergreen.

A source of fresh water is also necessary to maintain your bird population. The water source should be shallow (no more than 2″-3″ deep) and replaced on a regular basis. Running water, such as a shallow fountain, is the ideal water source. The water source should be elevated or in the middle of an open area to minimize predation by cats and other animals. An elevated bird bath or fountain is ideal.

A recommended list of trees and shrubs to enhance the bird population follows. Attributes that must be considered before selecting the trees/shrubs for your yard include, (1) the habitat element provided, (2) fruiting season, (3) deciduous (loses leaves in winter) or evergreen, and (4) size of mature tree (to fit with available space).

Trees and Shrubs for Attracting Birds
Southeastern Trees & Shrubs Provides: Fruiting Season Deciduous or Evergreen Size (sm, med, lg)
Cover Food
Beech X Fall, winter D M
Black cherry X X Summer D M
Black gum X X Summer D L
Blueberry X X Summer D S
Dogwood X X Fall, winter D M
Elderberry X Summer D S
Hawthorn X X Spring D M
Holly X X Winter, spring E M
Japanese yew X X Summer, fall E M
Magnolia X X Summer E L
Mulberry X Spring, Summer D L
Nandina X X Fall, winter E S
Oaks X X Fall D L
Pines X Spring, summer, fall E L
Pyracantha X X Fall, winter E S
Red cedar X X Fall, winter E M
Red maple X Spring D L
River birch X Summer, fall D M
Sumac X Fall, winter D M
Sweet gum X Summer, fall D L
Vibernum X X Winter E S
Wax myrtle X X Summer, fall E M

To make your yard more suitable for birds, conduct an inventory of trees/shrubs in your landscape and develop a table similar to that in this article. From this list, a) determine the mix of evergreen and deciduous trees, b) look at the time of fruiting and identify season(s) without food supply, and c) ensure that adequate cover and nesting habitat is provided. The following are two examples of possible situations in your yard and how to use the chart:

  • You have very few evergreen trees/shrubs (hence minimal shelter in the winter) but also have only small areas for additional plants. Select plants that are classified as evergreen (E) and are small sized at maturity. These plants (red cedar, nandina, viburnum, pyracantha, Japanese yew, holly, and wax myrtle) are relatively small trees.
  • You need a food source for the spring but have limited yard area available. An excellent solution is to plant hawthorn, especially mayhaws. They are a small multi-stem shrub that bear fruit in the spring and attract a wide variety of birds.

In most instances, you will find that the addition of a few carefully selected plants can increase the bird population in your yard.

Resource(s): Landscape Plants for Georgia

Center Publication Number: 163

Abiotic Problems of Citrus in Georgia

Source(s): Randy Drinkard

Citrus experience problems, such as:

  • fruit shedding,
  • leaf drop,
  • fruit splitting,
  • attack from insects and disease.

Fruit Shedding

Natural abscission of flowers and fruits prevents citrus from overproducing. Homeowners frequently become concerned about the excessive shed of young blossoms and fruits in early spring. This is a natural abscission of blossoms and fruits characteristic of all citrus. Another natural fruit shedding occurs in May and June when the fruits are marble sized. Only one or two percent (sometimes less than one percent) of the blossoms are needed for adequate yields.

Leaf Drop

Healthy trees lose large numbers of their leaves which is a natural leaf drop that may be most noticeable in early spring. Citrus leaves live for 18 to 24 months and then begin shedding, with some leaf drop occurring throughout the year. The homeowner should always be alert to other possible causes of leaf shedding, including mite damage, excessive or insufficient soil moisture, cold damage or root diseases.

Fruit Splitting

In late summer (August – September) fruit splitting may occur with certain oranges and tangerines. It usually occurs when a period of fruit growth cessation (associated with moisture stress) is followed by a rapid increase in fruit size as the result of heavy rain. Other than alleviating moisture stress, little can be done about the problem.

Citrus Insect and Disease Control in Georgia

Citrus fruits may be grown successfully in the home garden with little or no control of insects and disease. Fruits produced without pesticide sprays may be very poor in external quality as a result of damage by several mites, insects and fungus diseases. Although these unattractive fruits may have little eye appeal, this external damage usually has no detrimental effect on the internal fruit quality. The appearance of the tree may suffer, but trees are seldom critically damaged by most citrus pests. Natural biological controls will assist in maintaining pests at low population levels.

For those who prefer to spray, three cover sprays during each season should be sufficient. A post-bloom spray for scales, mites and fungal disease, a summer oil for scales and mites and a fall mite spray usually are satisfactory.

Formulating a spray program can be somewhat difficult because of the many factors involved. Government regulations are constantly changing regarding the use of agricultural chemicals. Consult your local County Extension Agent for information on developing a spray program for home citrus trees.

Resource(s): Citrus Fruits for Southern and Coastal Georgia


  • Steve Brady, CEA – Cobb County. The University of Georgia College of Agricultural and Environmental Sciences.
  • Jennifer Davidson, CEA – Muscogee County. The University of Georgia College of Agricultural and Environmental Sciences.

Center Publication Number: 173