Oak Leaf Galls

Galls on Oak Leaves

Tom Ingram: Ask A Master Gardener

Sunday, June 23, 2019

Q: I am noticing these round things about the size of a golf ball that appear to be falling from my oak tree. What are they? CS

A: What you are referring to is an Oak Apple Gall. They are called Oak Apple Galls because they kind of look like small apples. These curious growths are caused by a small wasp called a gall wasp. When the gall wasp lays its eggs, it injects a toxin into the host plant, which stimulates the tree to produce a protective cover around the eggs.

When the eggs reach larval stage, they begin to feed and develop inside the gall. When ready, they either emerge to create another generation or overwinter inside the gall, depending on the time of year.

A variety of gall types can form on leaves, twigs or branches. Typically, these galls do not harm the tree; however, a large outbreak could disrupt nutrient flow within a twig resulting in twig die-back. But this is the exception, rather than the rule.

There is another type of gall that can be problematic that is the result of gall midges. The gall midge lays its eggs on oak leaves and injects a toxin causing the leaves to form a gall that looks like a leaf with curled up edges.

Unfortunately, the larvae of the gall midge are the preferred food for the larvae of the oak leaf itch mite. Oak leaf itch mites can be problematic in that they are microscopic, and their bite can irritate our skin. In the height of an outbreak of oak leaf itch mites, it would not be unusual for potentially 300,000 mites to fall from the tree each day. That’s right, I said each day. Their bites can be painful, and some people will develop red swollen bite marks.

Unfortunately, treating your tree with some sort of pesticide is usually not an option due to expense and the fact that the insects are living inside the gall, which makes it hard for pesticides to reach them.

If you experience an oak leaf itch mite outbreak in your yard, the best advice is to stay away from the tree or wear long-sleeved shirts, long pants and a hat when working outside. That sounds like fun in an Oklahoma summer, doesn’t it?

You can best control these leaf galls through good sanitation: disposing of leaves and galls that fall to the ground. If a branch has a lot of galls and you can reach it, you could prune that branch and dispose of it.

The good news is that large outbreaks are rare in our area, but if you come in from working in the yard and feel a bite but don’t see anything, it just might be an oak leaf itch mite.

 Garden tips

• Vigorous, unwanted limbs should be removed or shortened on new trees. Watch for forks in the main trunk and remove the least desirable trunk as soon as it is noticed.
• Most varieties of mums are more productive if “pinched back” now. Either pinch off with fingers or cut to remove an inch or so of limb tips above a leaf. This results in the growth of new limbs and a fuller plant. Do not pinch after mid-July or it will interfere with fall blooming.
• Watch for tiny, sap-sucking insects called aphids on roses, perennial flowers, shrubs and vegetables (especially tomatoes). They produce a sticky substance called “honeydew.” Many can be dislodged with a hard spray from your garden hose, or two applications of insecticidal soap will usually greatly reduce any aphid damage to your plants.
• Crapemyrtles are one of the few shrubs that should be planted in the middle of summer. Growth of new roots of these plants occurs best with summer soil temperatures.

Coping with Too Much Rain and Flooding

Coping with Too Much Rain

Allen Robinson: Ask A Master Gardener

Sunday, June 9, 2019

Q: The amount of rain that we have received lately has been considered by some as unprecedented. What effects will this have on my garden and what should I do about it? Rebecca T., Tulsa

A: While most of us love the rain, too much of a good thing is rarely a good thing. So you are correct — too much rain can wreak havoc in the garden, which can happen in some rather unsuspected ways, such as:

Drowning

Perhaps the biggest problem is that too much rain can actually drown plants. Water sitting in the soil actually fills all of the subsurface voids that would otherwise contain essential oxygen for root and plant growth. When that happens, plants are simply not able to respire/breathe and, therefore, will eventually suffocate. Carbon dioxide and ethylene gases can also accumulate, both of which can be quite toxic to plants.

Symptoms of waterlogged soil include plant leaves turning yellow, turning brown or wilting suddenly. Short of waiting for the soil to dry out, there’s not much you can do to reverse the situation. A couple of tips to help: 1) Pull back the mulch from around plants to facilitate the drying process and 2) carefully stab a garden fork into the ground to help needed oxygen reach deeper into the soil.

Malnutrition

Too much rain can actually leach essential nutrients out of the soil, especially nitrogen. Nitrogen easily moves through the soil with just simple watering (potassium and phosphorus do not), and heavy rains just exacerbate the situation. So once the soil dries out a bit, consider applying a fertilizer that is high in nitrogen. Common types are Ammonium Sulfate (20-0-0), Ammonium Nitrate (34-0-0) or Urea (46-0-0). Milorganite and Osmocote are also good choices. Or simply top-dress plants with compost, which contains all of the essential ingredients.

Splash down

Mud that splashes onto leaves and stems often harbors fungal spores. If this occurs, simply wash the entire plant with a gentle mist. On plants that are particularly susceptible to fungal diseases (e.g. roses, tomatoes), consider applying an all-natural fungicide as a preventive measure.

Tread lightly

Be careful where you walk. Your weight (regardless of what it is) can cause severe compaction in wet soils, which is the enemy of plants. If you have to work in the garden, first, place a board on the ground, then walk on it to minimize compaction. Walking in wet soil can also hasten the spread of fungal diseases.

Infertility

Pollination can also be affected by heavy rains. This is because pollinators have a tough time flying in the rain and heavy, wet pollen simply isn’t as effective at doing its thing. There’s not much you can do to remedy this problem short of waiting for the weather to change.

Grass, anyone?

We have all been frustrated during those times when frequent rains make it impossible to get out and mow our lawns. And by the time it is dry enough to mow the grass, it’s overgrown. One way to conquer this is to double-cut the grass. Raise the mower deck to its highest notch, mow, then drop the deck height to your preferred level and mow again. The second mowing should be done in a different direction to the first mowing.

Now, we just need to find out who overdid the rain dance.

Get answers to all your gardening questions through the Tulsa Master Gardeners Help Line at 918-746-3701, at the Diagnostic Center, 4116 E. 15th St., or email mg@tulsamastergardeners.org.

Garden tips

• Renovate overgrown strawberry beds after the last harvest. Start by setting your lawnmower on its highest setting and mow off the foliage. Next, thin crowns 12 to 24 inches apart. Apply recommended fertilizer, pre-emergent herbicide if needed and keep watered.
• White grubs will soon emerge as adult June beetles. Watch for high populations that can indicate potential damage from grubs of future life cycle stages later in the summer.
• Fertilize warm-season grasses at 1 pound of nitrogen per 1,000 square feet. Don’t fertilize fescue and other cool-season grasses during the summer — wait for fall. Nitrogen, the first of the three numbers on all fertilizers, is very water soluble. So if you fertilized before the recent rains started, much of it may have been washed into deeper soil or drain water. After the rains have passed, consider re-applying a nitrogen-only fertilizer at the rate indicated above.

Common Problems When Growing Tomatoes and Suggested Solutions

Problems May Occur When Growing Tomatoes

Allen Robinson: Ask A Master Gardener

Sunday, May 12, 2019

Q: My family loves to eat fresh tomatoes off the vine, but I hear that growing tomatoes around here is a challenge. Can you tell me why it is difficult to grow them here and what I can do about it? Stacy H., Tulsa

A: You are certainly not alone both when it comes to loving tomatoes fresh off the vine as well as having trouble growing them in northeast Oklahoma.

One of the most common issues is known as “blossom drop,” which occurs from incomplete pollination. Weather is the chief cause of inadequate pollination in garden-grown tomatoes, with the most important factor being temperature. Effective pollination stops occurring once night temperatures are consistently over 75 degrees and/or when daytime temperatures are consistently over 92 degrees — especially if it is windy. Too much rain or too high or low humidity are additional weather factors which reduce pollen fertility. Also, overapplication of nitrogen fertilizer leads to blossom drop as well as tall, lanky plants and other diseases.

The solution to this is to plant very disease/pest resistant and healthy plants as soon as possible after the last frost has occurred. Then, pick the fruit as soon as it turns pink and let it continue to ripen indoors. Do not let it sit on the vine until it becomes overly ripened and soft.

Another common issue is called “blossom end rot,” where the fruit develops blemishes on the blossom end of the fruit. This is caused by a calcium deficiency in the plant when the fruit is young. Overwatering, either from nature or the gardener, is the most common cause rather than the lack of calcium in the soil. Keep the soil evenly damp as much as possible.

Skin splitting, called “cracking”, is also caused by plants going from too little to too much water. Be consistent about watering. Mulch plants to provide consistent moisture and temperature at the root level. Be careful to not mulch directly against the plant trunk as it can lead to diseases.

Speaking of diseases, avoid splashing soil on the plant and onto tomato fruits, as this carries related fungi and bacterial diseases. Instead, use either a soaker hose or drip irrigation system, or carefully water at the base of the plants. Avoid damaging tender roots by not hoeing too deeply or too closely to the plants.

In addition, there are several pests that love to live off the stems and leaves of tomato plants. For a listing of pests and how best to battle them, go online to tulsamastergardeners.org and search for OSU Fact Sheet EPP-7313 (Home Vegetable Garden Insect Pest Control).

Experts will say that the best weed control in a lawn is to simply grow a healthy, thick lawn which tends to crowd out weeds. The same is true for vegetables. Look for high quality varieties at reputable nurseries around town and ask which varieties are the most disease resistant. There are many varieties available.

Tulsa’s climate is a challenge to growing tomatoes in the summer. But, with a little attention to the details, you can have very good success. And, remember, there’s always fall.

 Garden Tips

• Don’t spray insecticides during fruit tree bloom or pollination may be affected. Disease sprays can continue according to schedule and label directions.

• Mowing of warm-season lawns can begin now. Cutting height for bermudagrass and zoysia grass should be 1 to 1½ inches high, and buffalograss 1½ to 3 inches high.

• Harden off transplants outside in partial protection from sun and wind prior to planting.

• Let spring flowering bulb foliage remain as long as possible before removing it. That will allow the energy from the leaf to flow back into the bulb for flower production next year.

• Prune roses just before growth starts and begin a regular disease spray program as the foliage appears on susceptible varieties

Crapemyrtle Bark Scale Insect Control

Crapemyrtle Bark Scale Insect

Brian Jarvis: Ask a Master Gardener

Sunday, April 14, 2019

Q: I have white spots that turn to a blackish mold on my crapemyrtles. What is it and how do I get rid of it? Tricia, Tulsa

A: We addressed this issue in this column last year, but some of the recommendations made by OSU regarding control have changed. The current recommendations come from Dr. Eric Rebek, state extension specialist for horticultural insects.

It is an insect pest that is called Crapemyrtle Bark Scale. This insect is relatively new to our area but has become prevalent. It came to the U.S. from Asia and first appeared in north-central Texas in 2004. It has subsequently spread northward into the Tulsa area from nursery stock and other sources of imported crapemyrtles. This is the reason one should always inspect nursery crapemyrtles for scale insect before purchase.

Like other scales, the life cycle begins with either the female scale or eggs overwintering on the crapemyrtle under loose bark. When the eggs hatch, small mobile “crawlers” are produced, which migrate on the plant and may be spread to other crapemyrtles by wind or birds. There may be two to three generations produced per year depending on temperatures.

Once the female is fully developed, she mates and attaches to the stems and trunks of the crapemyrtle, where she remains fixed and lays eggs for the next generation. She dies shortly thereafter, but the eggs survive under her covering until they hatch.

As the scales feed, they release a liquid called “honeydew.” This is like the behavior of aphids. The sugars in honeydew may support the growth of a fungus called “sooty mold.” This overgrowth produces large black patches on the bark of the crapemyrtle. The mold is unsightly, which creates a reduction in aesthetic quality, but it is not significant in terms of the plant’s health.

This pest is easy to identify because it is the only scale insect to infest crapemyrtles. The adult female is usually about 2mm long and has a distinctive gray-white felt-like covering. When one of the females is crushed, a pink blood-like fluid is released.

The current recommendations for control are removal by hand and the use of winter dormant oils. Scrub down the trunk of the crapemyrtle with a mild solution of dish soap and water using a long-handled brush to remove the scale and sooty mold. This method is very effective. Another recommended treatment is to spray the trunks of the trees with dormant oil in late winter. Winter dormant oil spray is a stronger concentration of the petroleum-based oil that is used in summer. Neem oil, while useful in other applications, will not be effective for this scale in winter.

Previously, systemic insecticides in the neonicotinoid family were recommended. These chemicals enter into the circulation of plants and kill the pest when they feed on the sap. They have been shown to be effective against crapemyrtle bark scale but are no longer recommended. The reason for the change in policy is the concern that these insecticides enter the blossoms of crapemyrtles and would be harmful to bees and other pollinating insects.

Garden tips 

• Don’t spray insecticides during fruit tree bloom or pollination may be affected. Disease sprays can continue according to schedule and label directions.

• Mowing of warm-season lawns can begin now. Cutting height for bermudagrass and zoysia grass should be 1 to 1½ inches high, and buffalograss 1½ to 3 inches high.

• Harden off transplants outside in partial protection from sun and wind prior to planting.

• Let spring flowering bulb foliage remain as long as possible before removing it. That will allow the energy from the leaf to flow back into the bulb for flower production next year.

• Prune roses just before growth starts and begin a regular disease spray program as the foliage appears on susceptible varieties.

Soil Temperatures Are Key to Spring Vegetable Garden Success

Starting a Vegetable Garden in Spring

Tom Ingram: Ask a Master Gardener

Sunday, March 31, 2019

Q: It’s so nice outside, am I safe to start my vegetable garden now? CT

A: Oftentimes, people will suggest certain dates when you can plant your vegetable garden. But dates are only guidelines. To know for sure when we can plant, we must look at the weather and do a little investigation to determine soil temperature.

For example, oftentimes, people will say St. Patrick’s Day is the time to plant potatoes. There is no potato magic in St. Patrick’s Day, other than in a normal year you are probably OK planting on this day. The truth about when to plant potatoes is based on when the soil temperature is appropriate for planting.

According to the OSU Extension, soil temps need to be above 50 degrees before we plant potatoes. At the writing of this article, soil temps at a depth of 4 inches are hovering around 51 degrees. So we’re just entering optimal conditions for potato planting.

Cold soils also inhibit seed germination of some of our more popular vegetables, such as tomatoes, squash, cucumber or peppers. To overcome this challenge, it is common for gardeners to start seeds indoors so the plants will be ready to go outside when it warms up.

If you have been to any of the garden centers in northeast Oklahoma recently, you will have noticed racks of seeds and seed starting supplies. Many of us have already gotten our seeds started and can’t wait to get them out in the sun. But if we move them outside too early, we run the risk of a late freeze damaging our fragile new plants. In northeast Oklahoma, we typically say we should be safe after April 15, which is still a couple of weeks away. But it’s not unusual for us to have a late freeze. Last year, we had one night with a low of 28 degrees the first week of April, so if you jump the gun, be ready to spend some time covering your plants.

Sometimes, talking about the need to find out what your soil temperature is at various depths can be a little intimidating. But don’t let that scare you off. In Oklahoma, we have a wonderful resource called the Mesonet. The Mesonet is a joint project between OU and OSU with at least one weather monitoring station in each county. You can visit mesonet.org for an abundance of weather information, including rainfall and soil temperatures.

For more information on starting and growing vegetables, visit the “hot topics” section on our home page to find a link that will take you to an abundance of information to help you be a more successful vegetable gardener.

Garden tips

• Our annual spring educational Lunch & Learn classes at the Tulsa Central Library downtown have begun.
• One of our most anticipated events is currently underway: The Master Gardener Plant Sale. You can choose from more than 200 plants, including annuals, perennials, grasses, herbs, tomatoes, succulents and stepables.

To find out more information on any of these and other opportunities, visit our website at tulsamastergardeners.org.

Oklahoma Proven Selections for 2019

Oklahoma Proven Selections for 2019

Allen Robinson: Ask a Master Gardener

Sunday, March 17, 2019

Q: Given our erratic weather patterns, is there a good way to know what plants, trees and shrubs grow well in our area? Sam R., Tulsa

Rattlesnake Master
MG Demo Garden

A: This is a good question that many people think about. And it’s a very reasonable request given the amount of labor involved in planting, as well as the cost of landscaping products these days. So wouldn’t it be nice if someone had already done the research on which plants do best in our neck of the woods? And also tell us where to plant them so they have the highest chance of success? Well, they have!

It’s called the Oklahoma Proven Program. Oklahoma Proven is an annual plant evaluation and marketing program coordinated by the Department of Horticulture and Landscape Architecture at Oklahoma State University. Designed to help consumers select the best plants for Oklahoma gardens, these plants are tolerant of the varied and difficult environmental conditions found throughout Oklahoma.

Every year, an annual, a perennial, a shrub and a tree are selected. The selections for 2019 are:

Annual: Star Flower (Graffiti® series) grows to 16 inches high and 12 inches wide, making it a great plant for containers or in a flower bed. They are very heat-tolerant, drought-resistant, make great cut-flowers and attract butterflies and hummingbirds throughout the summer months. Like all Pentas, Graffiti® prefers sun/heat, dry soil with good drainage but not too rich.

Perennial: Rattlesnake Master is a native species to the tallgrass prairies. Leaves are parallel-veined, bristly-edged and sword-shaped, with medium green leaves (up to 3 feet long) resembling those of yucca. Flowers are greenish-white and tightly packed into globular, 1-inch diameter heads resembling thistles. It prefers dry, sandy soils and is best left undisturbed once established. Perfect for a xeriscape garden, perennial border or native garden. Group plants in naturalized areas for the best effect.

Shrub: Flowering Quince (Double Take™ series) are hardy, deciduous shrubs reaching 4 to 5 feet high and as wide. It produces a profusion of early spring double flowers that resemble camellias. A thorn-less shrub with bold 2-inch double flowers, it comes in colors of scarlet, orange, pink and peach. Does not produce fruit. Very drought tolerant. If needed, prune lightly after it blooms in spring.

Tree: Limber Pine (“Vanderwolf’s Pyramid”) is an evergreen tree with a pyramidal habit that typically grows 2 to 30 feet tall and 10 to 15 feet wide. It is noted for its closely spaced, twisted, silvery blue-green needles. Being native to North America, it is an adaptable, low-maintenance tree with few problems, including being resistant to pine wilt disease.

Note: All of these plants do well in the Tulsa metropolitan area whose USDA Hardiness Zone is 7A (average low temperature of 0 to 5 degrees).

The Oklahoma Proven program has been in existence since 1999. The best part is that you can find every year’s selection back to 1999 online at oklahomaproven.org.

Remember that all plants need special attention during the establishment phase or during periods of environmental extremes. So be sure to give them some TLC until they get established. Then, watch them succeed!

While nothing in nature is guaranteed, you can significantly improve your odds by choosing Oklahoma Proven varieties.

Garden tips

• Remove flowers from spring-blooming bulbs after blooming is completed. This will allow the plant to direct its energy into its bulb for next year's blooms, rather than producing seeds. But allow foliage of these bulb plants to die and turn brown naturally before removal. As long as the leaves are green, they are storing energy for the following year. Fertilize them at the time of planting, in the fall or in the spring when their leaves first emerge.

• Cool-season lawns, such as bluegrass, fescue and ryegrass, may be fertilized now with the first application of the season. Usually, four applications of fertilizer are required per year in March, May, October and November. Never fertilize these lawn grasses in summer.

• Start your routine fruit tree spray schedule prior to bud break. Contact the Master Gardener office for a document outlining recommendations for all fruit tree types as they are not all the same.

Master Gardener’s Educational Programs Can Help You Succeed in the Garden

Master Gardener’s Educational Programs Can Help 

Brian Jervis: Ask a Master Gardener

Sunday, March 3, 2019

Q: After a few years of gardening, I am not happy with the results I am getting. How do I “up my game” so to speak? JF

A: That is a good question, and it is one experienced gardeners also deal with. We buy the plant, we do our best, and it still doesn’t thrive. Why?

There are a variety of factors that contribute to your success or failure.

• Did the plant get too much sun?

• Did the plant not get enough sun?

• Did the plant get too much water?

• Did the plant not get enough water?

• Was the soil chemistry appropriate for the plant?

• Did I fertilize properly and with the correct ingredients?

The list goes on and on, and we are not going to be able to cover the variety of variables in a single article.

But what we can do is tell you about all of the opportunities we have this spring for you that can help you become more successful.

First of all, our ever-popular Urban Gardener classes begin March 14. There are six classes on consecutive Thursday evenings where we will cover topics such as plant botany, pollination, composting, soil science, growing vegetables, pollinator gardens, shrubs and trees, and turf. These are fairly in-depth classes for beginners and those wanting to “up their game” as you said. The series costs $40 or you can sign up for individual classes for $10 each. If you are interested, you can sign up on our website.

Next, we have our Lunch & Learn classes at the Tulsa Central Library. For six Tuesdays from 12:10-12:50 p.m. starting March 26 we will have classes covering spring garden tips, tomatoes, fruit trees, pollinator gardens, seed saving and composting. Did you know the Central Library has a seed library where you can check out seeds? Find out about this and a variety of other topics in these free classes. Bring your lunch and learn from the Tulsa County Master Gardeners.

Can’t decide what plants to add to your garden this spring? Each year, we offer a huge selection of Master Gardener-approved flowers in our online plant pre-sale fundraiser. We have more than 200 annuals, perennials, herbs, tomatoes and grasses. Plus, this year we added succulents, steppables and a “sort” for pollinator plants so you can build your own pollinator garden. The shopping is easy (online) and when plant pick up day comes (April 18) you can drop by the Exchange Center at Expo Square, pick up your plants (we’ll even load them in your car for you) and shop a special selection of plants available in our one-day pop-up plant store. We will have a lot of milkweed available so you can do your part to help support the Monarch population this year.

More information is available for all these opportunities on our website: tulsamastergardeners.org.

Garden tips

• If you had previous damage to the tips of pine tree limbs, especially non-native pines, it may be diplodia tip blight (a fungus) or Nantucket pine tip moth damage. Both are controlled with pesticides starting this month. Call the Master Gardener office at 918-746-3701 for recommendations.
• Pre-emergent herbicide to control crabgrass should be applied by the middle of March.
• Divide and share with friends and replant overcrowded summer- and fall-blooming perennials.