Beautiful gardens by William Johnson

HERE ARE four questions for the dog days of August.
Q: Help! My satsuma tree has a heavy load of fruits but many of their rinds suddenly started to split one day recently. What caused this and what can I
do about it? 160810 Gardening Citrus rind splitting
A: After weeks and weeks of ample rainfall over the spring growing season, we entered into an extended period of drought conditions as early summer arrived.
The day following the first rainstorm that broke the drought a few weeks ago,
I started receiving inquiries about the cause of citrus fruit splitting. This type of damage typically occurs when citrus trees rapidly take up water from rain or irrigation after a long dry period. The fruit expands and bursts the peel in a crack across the bottom or blossom end of the fruit.
The buildup of excess fluids produces sufficient internal pressure to cause
the skin to burst. Young trees have the highest incidence of splitting, which occurs commonly on oranges, mandarins and tangelos. In contrast, grapefruits are rarely affected.
Maintaining adequate and even soil moisture levels by regular irrigation during extended periods of dry weather is the best defense against fruit splitting.
Q: The trunk of my pecan tree has several horizontal bands. Each band consists of a series of small holes evenly spaced up and down and around the trunk. It looks like someone used a drill
to make the holes. What caused them?
A: Several phone calls to my office this month were questions on the cause of a horizontal series of holes appearing on the trunk or branches of pecan trees.
The holes are spaced rather uniformly in distinctive rows around the trunk or even the tree’s major branches, with each hole being about the diameter
of a pencil and only about
a quarter-inch or so deep.
These holes are made by a woodpecker called the yellow-bellied sapsucker.  At least two reasons are provided in literature for why this particular woodpecker does this.
One is that the birds peck out holes to consume the sap and, indeed, they might show a preference for one tree in the yard and ignore another of the same species right next to it. In fact, these birds will return again and again to the same tree.
The other reason is that the yellow-bellied sapsucker pecks out the holes for the apparent purpose of providing a place for insects
to hide. The bird then supposedly returns periodically to eat the insects that seek refuge there.
In general, sapsuckers rarely cause serious damage to trees because the holes they peck are shallow.
Pecans are not the only trees affected by these woodpeckers, as oaks and other home-landscape trees are also frequent targets of the birds’ insect-mining efforts. If the holes had been random in occurrence, then the likely culprits would have been insect pests known as tree borers.
Q: I have small yellow insects crawling on my cucumber plants. Are they harmful and, if so, how can I control them?
A: The insects are most likely cucumber beetles, which are lime yellow with black spots.
They look somewhat like – and are often confused with – lady beetles but with longer bodies.
The most commonly occurring species of cucumber beetle in the county is known as the spotted cucumber beetle, which has 12 spots distributed over its body.
Cucumber beetles chew
on the young stems and leaves of cucumbers, cantaloupe, squash, pumpkins, watermelons, beans, peas and even okra, causing poor growth and yield.
You can spray insecticides such as Ortho’s Bug-B-Gon Lawn and Garden Insect Killer that contain esfenvalerate as the active ingredient on many of the vegetables mentioned. Check the insecticide’s label for specific directions.
Q: How often do daylilies need dividing? What is the best technique to use?
A: You should divide your daylilies every three to five years, depending on how crowded the plants are and whether flower production is declining.
Division is best done
in early spring, as new shoots begin to emerge,
or in the fall after the plants become dormant.
While most daylily varieties are quite tough,
I think it is beneficial to wait until lower fall temperatures prevail to dig them out. When dividing overcrowded plants, dig the whole clump.
Separate a clump’s plants by using two spading forks inserted back to back into the middle of the clump and then prying it apart. This is less damaging to the roots than cutting, which injures a large number of the plant’s feeder roots.
Cut the foliage back to about four inches from the ground.
If you are going to replant in the same location, first replenish the soil with well-rotted compost and a fertilizer high in phosphorus for root development. You may plant larger daylily varieties up to 30 inches apart and smaller varieties as close as 12 inches.
William Johnson is a horticulturist with the Galveston County office of Texas A&M AgriLife Extension Service. Visit his website at

Many home citrus growers have reported that the rinds of their maturing citrus fruit started splitting soon after plentiful rainfall ended the summer drought. This type of damage typically occurs when citrus trees rapidly take up water from rain or irrigation after an extended period of dry weather.
PHOTO CREDIT: William Johnson

Beautiful gardens by William Johnson

THE DOG days of August have arrived. Daytime temperatures have already danced around the century mark during the last week of July so there is no need to remind you that August is the peak of the heat season in Galveston County.160803 Gardening - Plumeria
Working outside this month tends to be more tolerable during the early-morning or late-evening hours. Given our present dry conditions, plants in the home landscape and garden will require attention if they are to remain vigorous and provide us with many desirable benefits including color, shade and beauty.
The county gardeners’ calendar of activities for August includes three seminars, all at the county’s AgriLife Extension Service office in Carbide Park, 4102B Main Street, La Marque. You can pre-register for any of them or all three by e-mail at or by phone at 281-309-5065.
Seminar on gardening by the square foot: Galveston County master gardener John Jons will discuss the basics of small-space gardening from 6:30-8:00pm on Tuesday, August 16.
Come learn how much you can grow in just a small 4ft x 4ft garden bed. Discussion topics will include planning, selecting plants, building the bed, maintenance and renewing the bed.
Seminar on flower arranging: County master gardener Jackie Auer, who has produced arrangements for the retail market and for private individuals, will demonstrate and explain the basic techniques of fresh- and artificial-flower arranging from 9:00-11:00am on Saturday, August 27.
Seminar on growing strawberries: Master gardener Robert Marshall will provide a class in how to grow strawberries successfully in our area from 1:00-2:00pm on Saturday, August 27. Topics covered will include the correct time to plant, choosing the best varieties for this area, how to prepare your garden beds, watering and fertilization, as well as disease and pest control.
Inspect trees before a storm: The Gulf Of Mexico has been rather quiet thus far during hurricane season. However, the peak season for tropical storm and hurricane formation occurs during August and September.
Inspect larger trees for broken, dead, damaged and weakly attached limbs as soon as possible before a tropical storm or hurricane threatens. Strong winds can tear such limbs from trees and turn them into dangerous projectiles. Also, inspect tree trunks for signs of structural damage. Obtain the services of a qualified tree-care professional as needed.
Large limbs are capable of causing damage to homes, vehicles and other property as well as causing harm to people in the event of violent weather. It is wise to consider calling a professional who has the training and equipment to avoid injury.
Divide perennials: It is time to divide spring-flowering perennials, such as iris, shasta daisy, oxeye, gaillardia, cannas, day lilies, violets, liriope and ajuga.
Rose bushes: A late-summer pruning of rose bushes can be beneficial. Prune out dead canes and any weak, brushy growth. Cut back tall, vigorous bushes to about 30 inches. After pruning, apply fertilizer and water thoroughly. If a preventive disease-control program has been maintained, your rose bushes should be ready to provide an excellent crop of flowers this fall.
Plumeria: In full bloom across the county right now, most plumeria flowers are very fragrant and some are downright intoxicating. Each flower can last for several days, whether on the plant or taken indoors and placed in water.
To perform at their best, plumeria require ample soil moisture. However, they do not tolerate “wet feet” so their root system must be provided with good soil drainage whether they are grown in containers above ground, in containers sunk into the ground or directly in the ground.
They are heavy feeders and will bloom and grow vigorously if provided the proper amount of soil nutrients. Plumeria enthusiasts recommend fertilizers that are low in nitrogen – the first number – and high in phosphorous – the middle number – such as Super Bloom, Carl Pool’s BR-61 or Peters Super Blossom Booster 10-50-10.
Other specialty plumeria fertilizers can be used as well. Plumeria growers typically fertilize at least every two weeks during the growing season.
William Johnson is a horticulturist with the Galveston County office of Texas A&M AgriLife Extension Service. Visit his website at

Plumeria will bloom and grow vigorously if provided adequate soil moisture and fertility.
William Johnson

Beautiful gardens by William Johnson

TYPICALLY, IN July I start receiving inquiries from concerned homeowners about strange misshapen growths on the leaves of their oak trees. These growths, known as galls, are often the result of certain types of insect depositing their eggs or feeding on the leaves.
The tumor-like growths are produced by a plant in response to chemicals secreted into its leaf tissues by the larval stage of gall-making insects. The shape, size and form of the gall are determined by the precise “cocktail” of chemicals produced by each species of gall-maker.
The mechanisms of gall formation and the way in which the chemicals result in very distinctively shaped galls are still poorly understood.

160727 Gardening - leaf gall on oakHomeowners may encounter strange, misshapen growths on the leaves of oak trees from late spring to fall. These growths, called galls, are often the result of the larval stage of very small wasps feeding on leaf tissue. Most galls rarely cause much harm to plants. PHOTO CREDIT: William Johnson

Most gall-making insects are tiny wasps. By tiny, I mean smaller than a gnat, smaller than a fruit fly and, in some cases, as small as a grain of pepper. These wasps are harmless to people or animals.
The interesting thing is that each species of gall-making insect makes its own distinctive gall — distinctive enough that it is possible to identify the species of wasp or other insect that creates each gall. While galls can occur on any tree species, oak and hackberry trees are the most commonly affected in our area. It’s not usually difficult to find several types of gall on a single tree.
Gall formation usually takes place in the spring, when leaves are rapidly growing. However, the final results are not noticed until later into the spring-and-summer growing season.
During spring, gall-making wasps deposit eggs on young oak leaves. The cells within the young leaf are rapidly dividing and the larva of gall-making wasps can alter new cells’ development and cause an oak leaf to grow a specific type of protective gall that will serve as a home for the wasps’ developing offspring.
Once a leaf or stem has stopped growing – ie, cell division has stopped – these hormone-like chemicals can no longer affect the plant.
The purpose for insect-
induced galls seems to be to provide a sheltered feeding site for gall-making insects’ developing young. Because galls provide benefit for the insect at little expense to the plant – only a very few galls seem to affect plant growth or overall appearance significantly – this is sometimes referred to as a form of commensal relationship.
In our area, the two galls most commonly encountered on oaks develop on the underside of their leaves. One, up to one-fourth-inch diameter, looks like small grapes or marbles that range in color from red to yellow or creamy white. The other is yellow to brown in color and looks like the end of a cotton swab.
Once a gall has formed, control by insecticide is not possible, but the good news for the tree owner is that leaf galls do not cause significant harm to the tree’s health.

Fall vegetable seminar

AUGUST signals the start of the fall gardening season. Even though we’re still struggling through the heat of mid-summer, novice gardeners can overlook the fact that, in Galveston County, August and September are times to plant many popular fall vegetable crops.
Many will have a longer harvest period than those planted in the spring as they mature during the cooler temperatures of the fall season, in contrast to spring crops that mature as the summer heat sets in. In fact, fall-grown vegetables have better flavor and are of higher quality than spring crops.
To start on the right track, come to an educational program titled Successful Fall Vegetable Gardening from 9:00-11:30am on Saturday at the Galveston County AgriLife Extension Service office in Carbide Park, La Marque.
Pre-registration is required to ensure availability of handouts. Call 281-309-5065 or e-mail
Certified Texas master gardener Luke Stripling will be program speaker. Luke, who has accumulated a wealth of knowledge and hands-on experience on home vegetable gardening, will provide information on topics including soil preparation, vegetables that do well during the fall and winter, variety selection, fertilization and pest control.
Successful fall gardening begins much earlier than the official start of the fall season and proper timing is probably its most important factor. If you start this month, fall will be a great time to garden in Texas.
William Johnson is a horticulturist with the Galveston County office of Texas A&M AgriLife Extension Service. Visit his website at

Johnson, William            William Johnson

Beautiful gardens by William Johnson

WITH A great deal of home-landscape foliage reaching its most luxuriant period of the year, it is hardly strange that, recently, I have received several questions all asking about the health of plant leaves.
Q: My orange and satsuma citrus trees have a problem. Their newest leaves look strange. They have become twisted and shriveled and I don’t know what to do.
A: The damage you describe on your citrus trees is caused by an insect known as the citrus leafminer, the adult stage of which is a tiny moth. The female moth lays her eggs on tender, new growth. This typically occurs on the late summer and fall flushes of new growth.
After the eggs hatch into larvae, they enter the leaf and feed on the inside, creating a silver sheen, serpentine trails and twisted, deformed leaves. The larvae eventually emerge from the leaf and make a pupal chamber by folding the edge of the leaf down and securing it with silk.
You will reduce the amount of damage if you begin a spray application with an organic insecticide containing spinosad as the active ingredient as soon as you begin to see new leaf growth or as soon as you see the first symptoms. 160720 Gardening Citrus leafminer
Gardeners can obtain spinosad at local garden centers under different commercial names, including Green Light’s Spinosad and Ferti-lome’s Borer, Bagworm, Leafminer & Tent Caterpillar Spray and other brands.
Citrus leafminers are not active from late fall to late winter when daytime temperatures consistently stay below 85°F for extended periods – typically from November to March. Applying insecticides might not be particularly effective by the time most home gardeners realize there is a problem and decide to do something.
Fortunately, in most situations the damage looks a lot worse than it is. Affected trees generally recover very well and no reduction in harvest occurs.
Q: My fig tree produced a good crop this year but many of the leaves at the top of the tree have developed black spots and about one third have fallen off. What can I do to deal with this and prevent damage?
A: The leaves are exhibiting symptoms of a fungal disease known as fig rust. Leaf spots are likely to increase as we move into the fall and rainfall becomes more generous.
Early symptoms of fig rust include leaves developing small yellow to yellow-green spots that enlarge and take on a brownish tinge as they spread. With time, the leaf yellows, shows browning at its edges and curling.
The spotted leaves will eventually be shed. As it is happening early this year, we could see our figs put on a second flush of leaves.
Although the spotting and leaf loss do not look good, the trees tolerate the disease well and suffer no long-term health effects provided good soil moisture levels are maintained.
While no fungicides are available to treat fig rust, I highly recommend raking up dropped leaves to help reduce disease development. The fallen leaves harbor the fungal disease pathogen.
When rust-infected leaves drop, try to gather them in plastic bags for curbside trash pick-up. If rust-infected leaves are not removed, they will infect new leaves as they come on. Your tree should leaf out normally next spring with lots of healthy leaves.
Q. The leaves on my well-lit indoor schefflera contain numerous bumps and a clear sticky material that drips onto the carpet. What’s the cause and how do I treat it?
A: The most likely problem is an infestation by scale insects that produce honeydew, the clear, sticky, sap-like substance you describe. While aphids and certain other sucking insects can also produce honeydew, scheffleras are more likely to be infested with scale insects, which appear on the twigs and leaves as off-white to brown bumps that you can scrape off with a fingernail.
Scale insects are difficult to control, especially if they have spread to other plants. Treat them with an insecticide labeled for use on interior houseplants. Insecticidal oils, such as neem oil, and soaps, such as Safer’s Insecticidal Soap, might be your best option if the plants must be kept indoors during treatment.
Insecticidal soap or horticultural oil will kill scales but at least three treatments are usually needed for severe infestations.
William Johnson is a horticulturist with the Galveston County office of Texas A&M AgriLife Extension Service. Visit his website at

The new growth of citrus trees is susceptible to feeding damage caused by the larval stage of an insect pest known as the citrus leafminer. PHOTO CREDIT: William Johnson

Beautiful gardens by William Johnson

REACTIONS to plants and the little bugs and beasties that inhabit their leaves can be quite severe. I recently received two questions that highlighted the need for information on how to avoid a less than welcome brush with nature.
Q: Recently, I developed a contact rash from handling pruned oleander branches. Two days later, I was covered in spots and a rash on both arms. Do plant reactions tend to happen right away or can they take a couple of days to present, especially with regard to oleanders?
A: Most local gardeners know oleanders are quite poisonous but that factor is generally related to ingestion of leaves, seeds or other plant tissue.
I was not surprised about the skin rash issue but I contacted Betty Head, who is a BOI Galveston resident and longtime member and a past president of International Oleander Society.

160713 Gardening Io caterpillerIo caterpillars, which like feeding on blackberry plant leaves, are among several species of caterpillar that sting. As a precaution, look before pruning or reaching into plants and learn to identify the stinging caterpillars that live in our area. PHOTO CREDIT: Robbin Collins

Betty was not surprised either and reported that sensitivity to the oleander sap is not common but has been reported.
Even so, we both recommend wearing protective clothing, including long sleeves and pants, when pruning oleanders.
If you prune during the warmer part of the day, sweat would tend to aggravate the spread of sap on the skin. Similar to rash development after exposure to poison ivy, people with sensitivities to the sap of fresh-cut oleanders can develop rashes in a matter of a few hours or as long as several days after contact.
Always seek the advice of your physician or other qualified healthcare professional regarding any medical treatment.
Q: Clusters of lime-green caterpillars are feeding on my blackberry plants. What are they and what can I spray to control them?
A: Caterpillars of all kinds make an appearance during the summer. Armyworms, webworms and orange dog caterpillars are all generating calls to my office. Some are ferocious looking but harmless. However, there are a few that, if touched, will gain your immediate attention. Stinging caterpillars can be found on a variety of home-landscape plants.
When people think of stinging insects, they typically think of bees and wasps, not caterpillars. However, several species of caterpillar sting. They usually show up at this time of year and are most often found feeding on the leaves of trees and shrubs. Stinging caterpillars are likely to be more common this year than usual because of the unusually mild winter.
While there are several species of stinging caterpillars that occur in our area, the Io caterpillar is the most reported thus far.
They are referred to as stinging caterpillars but they do not possess stingers. Instead, stinging caterpillars have spines that are connected to poison glands. When touched, the tips of the spines break and release the poisonous chemicals that serve as a defense mechanism to protect the caterpilar from predators.
Many caterpillars have spine-like projections that resemble those of stinging caterpillars but are harmless. There are no general characteristics that differentiate them from the stinging types, so it’s best to leave them alone or learn to identify them and know their host plants. In general, don’t handle caterpillars if you are unsure of their identity.
Io moth caterpillars may reach 2.5 inches long. They are a striking chartreuse green color with well-defined red and white stripes running the length of their bodies.
Distinct groups of long yellow or green spines tipped in black cover most of the body of Io caterpillars, which have voracious appetites and can quickly strip leaves from host plants.
They feed on more than 100 recorded plants, including oaks, azaleas, roses, corn, elm, hibiscus, willow, ixora and palms. This is the first report of Io caterpillars feeding on blackberry plants.
Io caterpillars feed side by side as a family group in their early stages of growth and they can consume entire leaves in a short time.
If control is needed, spray young caterpillars with insecticides such as Dipel or BT that contain bacillus thuringiensis as an active ingredient. Older and larger caterpillars should be sprayed with insecticides such as Sevin containing carbaryl as an active ingredient. Alternatively, if you would like to control them mechanically, remove them carefully with forceps and dump them into a container of warm soapy water.
If you touch a stinging caterpillar, use adhesive tape to remove spines and apply ice packs or a paste of baking soda and water to reduce the stinging sensation. Anyone with a history of allergic reactions, hay fever or asthma should contact a physician.
Initial reaction to contact with a stinging caterpillar is severe burning and pain, numbness and swelling in the affected area. You might experience difficulty with speech and breathing. Allergic reactions can include nausea, vomiting, fever, shock and convulsions.
As a precaution, look out for caterpillars before pruning, picking berries or reaching into plants and learn to identify the stinging caterpillars that inhabit our area.
William Johnson is a horticulturist with the Galveston County office of Texas A&M AgriLife Extension Service. Visit his website at


THE FOLLOWING Galveston County Master Gardener Association programs are free to the public. All will take place at the county’s Texas A&M AgriLife Extension Service office in Carbide Park, 4102 Main Street, La Marque.

For course reservations, call 281-534-3413, extension 1 and then press option 2, or e-mail

For more information, go online to

A Homegrower’s Guide To Weed Control

WHAT: County master gardener Jon Johns will present a comprehensive, illustrative and entertaining program on identifying, managing and controlling the weeds in your garden. This program is appropriate for both new and experienced gardeners.

WHEN: 6:30-8:30pm, Tuesday, July 19


WHAT: County master gardener Robin Collins will explain what an aquaponics system is, how to set one up and maintain it and the advantages of using aquaponics over more traditional methods of growing vegetables and herbs. Included in the presentation will be information about the wide variety of herbs and vegetables that grow successfully using this method, as well as how to select the fish to use in a home system.

WHEN: 9:00-10:00am, Saturday, July 23

Successful Fall Vegetable Gardening      

WHAT: Long-time master gardener Luke Stripling will present a program on growing cool-weather vegetables in the county. Topics will include soil preparation, drainage, the use of raised beds, the use of fence or other supports, the best seed-planting dates, the best varieties, planting depth, fertilizer methods, water requirements and harvesting.

WHEN: 9:00-11:30am, Saturday, July 30