Q: What are these bumps on my Cactus?
A neighbor recently emailed about a cactus problem. It appears to be oyster shell scale. Scale insects have six legs and appear insect-like only in the “crawler” stage that hatches from the egg. It is the crawler stage that spreads the infestation to the new plant growth and nearby host plants by hitching a ride on animals such as birds, or on clothing or even by being blown by the wind. Once the crawlers settle down, they insert their sucking mouthparts into plant tissue and begin feeding. They generally no longer move and slowly develop to the adult stage. The females weave a silk-like web that hardens into a shell that protects her and her eggs. In some species, winged six-legged males emerge to mate with females. Oyster shell scales are armored scales (Hemiptera: Diaspididae). Adult females appear as round or oval white spots with raised areas on or off the centers. Males can be elongate and white. Their presence is unsightly, and high numbers can stress plants.
Recommended solution: This is a difficult scale to control but two different methods are recommended. You can choose the method depending on the amount of work you want to put into it and the number of affected plants you have. And remember, even when killed, dead scales will remain on the cactus pads due to the females hard shell.
The first method is the easiest if you just have a few affected plants. Use isopropyl alcohol or rubbing alcohol. For hard skinned cacti use a soft brush such as a nipple brush for a baby bottle or a straw cleaner. If you are treating a succulent or thin skinned plant, use Q-tips. Dip brush or Q-tip into alcohol and rub the scale. Be gentle on the thin skinned succulents. As you’ll see, the scale comes off readily. You may have a few stuck in nooks and crannies you can’t remove but just dab on the alcohol to kill them.
The second method is a bit messier. You will need Neem oil, not dormant oil or horticulture oil. Mix the neem as directed on the label, they are all different. Move all affected plants out of the sun for protection. Place an old sheet or some protection underneath your plants. Spray them to saturation with the Neem oil mixture. Keep them out of the sun for 7 days and repeat the process. After another 7 days, spray the plants well with a strong stream of water to remove any residual oil … some scale may come off also. You can now safely move the plants back to the sun. If you use the oil in the sun your plants will suffer from sunscald and possibly die.
Photo Credit: John Morton
Q: What is Entomosporium Leaf Spot and what do you do about it?
From Deborah Birge, Fort Bend County Master Gardener
Entomosporium leaf spot is a fungal disease particularity evident on Indian Hawthorne and Red-tip Photinia. The fungus survives in infected leaves on the plant or on the soil beneath the plant, and spores are dispersed by splashing water from rainfall or irrigation. This is why members of the rose family should never receive overhead irrigation. As a matter of fact, thanks to their drought tolerance and more than enough rainfall here, Indian hawthorns almost never need any irrigation in our area. Water on the leaves is required for infection to occur. Young, growing leaves are most susceptible to infection, and the disease develops rapidly during the cool, wet weather of spring and fall.
If you have further questions, please contact the Fort Bend Master Gardener Hotline and Research Team at FortBendmg@ag.tamu.edu
1. Purchase only healthy plants that do not show leaf spot symptoms.
2.Space plants adequately to allow good air movement. This helps to promote rapid drying of leaves and reduces the chances of infection.
3.Remove fallen diseased leaves, particularly in the winter prior to the plant’s new growth in the spring. This reduces a source of fungal spores available for new infections.
4.Water only when necessary. This prevents excessive new tender growth. When it is necessary to water plants, do it early in the morning to allow the leaves to dry faster with the morning sun. This minimizes the time that the foliage stays wet. Surface or drip irrigation is the preferred method of watering since the leaves remain dry. Alternatively, adjust sprinklers to reduce or prevent splashing and wetting the foliage.
5.Prune plants selectively and infrequently to help prevent excessive new growth
6.Avoid fertilizing the plant during the summer to limit excessive plant growth. New, succulent growth increases the susceptibility of the plant to infections.
7.Fungicides, such as thiophanate-methyl and myclobutanil, can be used effectively to prevent Entomosporium leaf spots when conditions become favorable for developing the disease, such as in cool, wet weather with diseased plants growing nearby.
Always refer to product labels for instructions on proper usage of the fungicides. Fungicide applications are not necessary during hot, dry periods.
Q: What is torpedo grass and what do you do about it?
From Deborah Birge, Fort Bend County Master Gardener
There is a new invasive grass/weed in the area. It’s called Torpedo grass (Panicum repens), creeping panic, panic rampant, couch panicum, wainaku grass, quack grass, dog-tooth grass, or bullet grass. I particularly like creeping panic since that is what one feels upon finding a healthy growth of this grass in their lawn. It is present in many places as an introduced species and often a noxious weed. It has been called “one of the world’s worst weeds.”1
Torpedo grass was introduced to the US in approximately 1876 as a forage grass. It can grow up to 3 feet tall on long, strong rhizomes. It has been noted to grow 1.3 centimeters or 0.51 inches in length per day. It enjoys sun or shade, soil or water. It can withstand grazing cattle, floods, drought and fire. It can be made into hay or used to stop erosion. But, it’s almost impossible to destroy.
When hand-pulling or mowing, the rhizomes can break apart. As a portion falls to the ground, it will sprout roots and anchor itself. The plant survives and sprouts after herbicide application, grazing, cutting, plowing or disking, and burning. The grass rarely reproduces by seed.2
Eliminating torpedo grass in the lawn is a tricky business, requiring tenacity and usually multiple chemical applications. The weed is nearly indestructible and has been known to come out through weed barrier fabric.3 There has been some success using the chemicals glysophate or quinclorac. The problems are that these chemicals will also kill your Bermuda or St. Augustine grass. Although you might start to think this would be a good trade-off, remember that a bare spot in your lawn will attract even more weed seeds.
All recommendations for control have shown unpredictable results. Applications of herbicide must be used repeatedly until the rhizomes are dead. A promising plan is to use a pre-emergent labeled for crabgrass in the fall. In the spring attack the sprouting torpedo grass with glysophate or quinclorac. Quinclorac is easier on Bermuda grass than glysophate. After the rhizomes are dead, re-sod. Always follow label directions when using any chemicals. Monitor your lawn for new eruptions and treat accordingly.
For more information, you can follow this link http://www.tsusinvasives.org/home/database/panicum-repens
Photo credit: Lee Legrand
- Byrd, J. D. and V. Maddox. Torpedograss (Panicum repens L.) Mississippi State University Extension
- Stone, Katharine R. 2011. Panicum repens. In: Fire Effects Information System, [Online]. U.S. Department of Agriculture, Forest Service, Rocky Mountain Research Station, Fire Sciences Laboratory
- Torpedograss Weeds: Tips On Torpedograss Control, Bonnie L. Grant, Certified Urban Agriculturist
Q: What’s Eating My Citrus?
From Deborah Birge, Fort Bend County Master Gardener
It’s that time of year when we receive numerous calls from the Fort Bend community asking, “What’s eating my citrus?” This has become an all too often sight for home growers. Grackles begin migrating into our area about the same time as the young citrus begins to develop. These birds, along with Mockingbirds, begin pecking on young fruit. Injured peel tissue becomes blackened and develops a pock-marked, scratched surface cosmetically unacceptable for the commercial grower market. For home growers, it is considered a minor problem unless the birds penetrate the flesh, thereby spoiling the fruit.
There is speculation that most of the damage is committed by juvenile birds. They use the small junks of peel to rub their feathers. Whether this is to look slick and smell good, or to deter mites, no one knows. It could be similar to “anting” which appears to be widespread and common but not readily observed. Most information is anecdotal. More than 200 species of birds — mostly songbirds — have been observed to ant. The ants come from two subfamilies, they don’t sting, and they produce defensive secretions to repel attackers. Ants in the first and largest group produce formic acid, which they eject from the tip of their abdomen. In the second subfamily, a repugnant oily liquid is secreted from anal glands. https://www.birdwatchingdaily.
Efforts to prevent grackle and mockingbird damage have met with only limited success. The birds become indifferent to visual exclusion methods such as flapping ribbons, twirling CDs or artificial snakes and owls. Bird netting is often suggested as a deterrent, but birds being caught in the netting with all the problems that come of that could make one think twice. Another exclusion tactic is to spray the fruit with a kaolin clay solution. This turns the fruit white which seems to confuse the birds. The only drawback is removing all the clay if you wish to market the fruit.
Lastly, there is the use of organza bags. These bags are sold as bridal gift bags and come in a variety of sizes and colors. These bags are used as a pest exclusion on several different fruit with several different results. It does work to prevent birds from pecking the fruit but can be a tedious and thankless job to bag several hundred citrus fruit.
All in all, the bird damage is unsightly but causes no real damage to the fruit. Enjoy your summer in the cool of the house watching the cunning and colorful birds. This will remain one of the more interesting mysteries of the avian kingdom.
Q: What are spider mites?
From Deborah Birge, Fort Bend County Master Gardener
Spider mites love our hot, humid summers and are the most common pest complaint this time of year. The mites, which are actually arachnids, multiply rapidly on the shaded underneath of leaves and are so small you don’t notice them until you see leaf damage. Mites feed on the cells of leaves causing a puckered, mottled appearance, silvering or bronzing of the leaf. Leaves will eventually fall off.
If you have a handheld magnifying glass you will see small, red, spider-like critters with eight legs. If you see white bodies, you are not seeing white flies but the cast-off skins of the mites. You may see some webbing but not always.
What to Do?
1. Healthy plants are less likely to attract pests. Spider mites are attracted to water stressed plants.
2. Look for beneficial insects such as lady beetles, are they doing their job?
3. If possible, isolate the plant.
4. Wash the plant with a strong stream of water to remove the mites. Be sure to focus under the leaves and wash several times per week.
5. A spray of neem or a light, summer oil will smother the adults and eggs.
6. Avoid using pesticides since many spider mites are resistant to these sprays. Additionally, you can make your situation worse by killing beneficial insects working to decrease the population.
For more information, see https://texasinsects.tamu.edu/spider-mite/
From Deborah Birge, Fort Bend County Master Gardener
This is the time of year many gardeners will be perplexed as to why their healthy vegetable plants suddenly begin to turn yellow and drop leaves and produce. Hot, wet weather is the perfect environment for Southern Blight. SB is a serious and destructive fungal infection that attacks plants at the base. This infection survives in the soil and can multiply quickly. To get rid of the fungus is nearly impossible, so prevention is key, by using good garden management.What is Southern Blight of Pepper Plants? Caused by Sclerotium rolfsii, this disease is also known as southern wilt or southern stem rot. Plants affected by southern blight include: Peppers, carrots, potatoes, tomatoes, sweet potatoes, cantaloupe, and beans. The fungus attacks plants initially on the stem, right at the soil line. One of the earliest signs of the disease is a small, brown lesion on the stem. You may later see a cottony, white growth around the stem near the ground, but symptoms also show up throughout the plant. Plants with southern blight have yellowing on the leaves, which will eventually turn brown. Eventually, the disease will cause the plants to wilt. The other signs of the disease are not always easy to notice, so it is typical to identify the problem only once the plants have begun wilting. At this point, the health of the plants may decline rapidly.
Preventing or Managing Southern Blight
Plant vegetables on a raised berm to ensure good drainage. Space plants to ensure air circulation. Rotate crops, plant resistant varieties. Previous crop residue should be buried deep enough to prevent its being brought back up in land preparation and cultivation. The fungi require oxygen for development. Keep fallen leaves or other organic matter from the base of the plant. Use foliage fungicides to prevent foliage diseases. Fungicides may also be applied to the soil on certain crops. This will inhibit development of the fungus.
Peppers Southern Blight Of Pepper Plants – Managing Peppers With Southern Blight Peppers By: Mary Ellen Ellis Printer Friendly Version Image by University of Georgia Plant Pathology, Bugwood.org
Q: What’s wrong with my peach tree?
Bacterial Spot (bacterium – Xanthomonas campestris pv. pruni): Bacterial spot is first noticed as small, pale green spots on the tips of leaves. Soon they begin to cover the leaf. The inner portion of the spot often falls out giving the leaf a “shot-hole” appearance which is another name for this disease.
Leaves heavily infected with bacterial spot turn yellow and fall. Repeated infection can occur throughout the growing season if there is enough rain. Symptoms first appear on fruit as small, olive brown, circular spots. Spots become slightly darker and depressed as the bacteria develops. Lesions are scattered over the fruit surface and tiny cracks develop in the center of the spots. Leaf infection is more common than fruit infections.
The bacterium overwinters in protected areas such as cracks in the bark, leaf scars that were infected the previous season and fruit mummies left on the ground or in the tree. As temperatures rise over 65 degrees Fahrenheit and budding begins, the bacteria begin to multiply. They are spread from cankers via dripping dew, splashing rain, overhead irrigation, and wind.
Keep your peach trees healthy by properly pruning out any diseased or dead limbs and fertilize and water as necessary. Too much nitrogen can aggravate the disease. Pick up all fallen leaves and remove any spent fruit.
Recommended solution: While there are no completely successful sprays for control of this disease, chemical spray with copper based bactericide and the antibiotic oxytetracycline have some effect used preventatively. Spraying with a Bordeaux mixture and some formulations of copper are acceptable as an organic solution. Look for products such as Copper Hydroxide, Ziram, Spreptomycin Sulfate. Spray at leaf fall or from November 15 to December 1 before winter rains to protect against twig infections.
Additional information can be found at https://plantdiseasehandbook.tamu.edu/food-crops/fruit-crops/peach-apricot-and-nectarine/
Q: Leaking tree?
Homeowners in Fort Bend County treasure their trees for their beauty, addition to property values and for protection from the Texas summer heat. Unfortunately, the beauty and health of our trees can often be threatened by environmental stress. This stress could be foot traffic during wet seasons, too much water, not enough water, mechanical injury, infectious diseases, or insects. One such disease is first noticed as a leak in tree bark.
Prevention is the key.
- Avoid wounding the tree.
- Plant trees in locations where there are no stresses from urban soil compaction, such as walking and vehicle traffic.
- Trim broken, torn branches promptly.
- Fertilize only when necessary.
There are no active measures to effectively treat the rot caused by slime flux disease. The best advice is to maintain the tree’s overall health so that it can compartmentalize the spot and grow good wood around the diseased area. The use of insecticides applied in the hopes of preventing the rot from spreading within the tree has been shown to be of no use. The urge to try this treatment is because people often notice insects feeding on the rot, but it should be remembered that the insects have not caused the disease nor do they spread it. There is even some opinion that by removing the decaying wood, insects may actually help the tree. Spraying for insects in an effort to cure slime flux is a waste of money.
Q: What do I do about ants in my pots?
It’s spring time and ants are looking to relocate to drier locales; most likely, your potted plants. This is not only inconvenient but can be damaging to the roots of your plants.
There are several methods of ridding the pots of ants but first you need to know your enemy. Baits are ant-specific so know what your are working with. One method of quickly removing ants is to drench your pot repeatedly with soapy water. One tablespoon of dish soap to one gallon of water works well. However, unless you move the container, the ants will return. More permanent solutions are included in the links below:
Q: Why are my Caterpillars Leaving?
Many of us are enjoying the arrival of butterflies and are excited to aid in the reproduction of these beautiful creatures. We’ve planted host plants and nectar plants but wonder why are some leaving the flower bed? Entomologists speculate that caterpillars leave their host plants to protect themselves from predators. “Caterpillars frequently strip the plant, so to form a chrysalis on a naked plant would leave them terribly exposed,” said Mike Quinn, an entomologist and founder of the Austin Butterfly Forum.
Given the above, and the high incidence of caterpillar mortality caused by birds, spiders and other predators, some are inclined to bring those wandering caterpillars inside to assure they have the best chance of completing their life cycle. Reasons for relocating a caterpillar would be to prevent overcrowding and chrysalis tampering from other caterpillars and to prevent hatching butterflies from spreading potential diseases to feeding caterpillars as explained at https://bugguide.net/node/view/203352.
Q: What’s Biting Me?
Many Fort Bend residents are complaining of biting gnats. Some call them No-see-ums but you can certainly Feel-um and their painful bite! The gnats swarm the head and neck leaving large itchy whelps. Well, they are not gnats at all. They are a species of black fly.
A quick solution is to wear long sleeves and pants, hat and with a bug net that covers your head and neck. If you don’t have a net any product with DEET will keep them at bay. Some have reported success with Avon Skin so Soft, Coleman Skin Smart, Deep Woods Off, Sawyer picaridin repellent, and Cutter Backwoods. Additionally, some local reports indicate that herbal and essential oil based repellents work well, although there is no re-search to support it. For more information, https://fortbend.agrilife.org/recent-outbreak-of-biting-flies/ .
Q: My crape myrtle started having these white spots on the tip of the leaves. Can you please advise?
This is something you just don’t need to worry about. This is guttation…what? Yep, guttation is the tip deposits of minerals left behind when plant fluids evaporate. So, nothing to worry about.
Q: How do I protect my plants from winter freezes?
When the year becomes the season of witches and goblins, quickly becoming the season of turkeys and pumpkin pies, growers of tropical and semi-tropical plants, begin planning for early frosts and winter freezes. The spring is often a time of mushy brown leaves, burnt foliage and twigs, split bark and damaged fruit, so early planning is a must.
We will begin this article by explaining how plants turn into those mushy messes after a freeze. Explained very simply, when the temperatures begin to drop, foliage and fruit will begin to lose their heat. The water inside a plant freezes causing ice crystals to form. These crystals break the plant’s cell walls. When the temperature warms the cells lose their fluids, die and turn to mush.
Our most common challenge is the marginal freeze. This only lasts a few hours with temperatures dropping to below freezing in the early morning hours, then back up above freezing by mid-morning. This is a quick temperature change, not too unpleasant but enough to kill any buds or blooms on fruit trees. By planning ahead, we can do a lot to protect our plants. Additionally, the less wind involved, the more effective our efforts.
Our most dreaded challenge is the “Nor’easter” that blows in a few times each winter. It is usually accompanied by high winds, rapidly falling temperatures and rain or sleet. There is little we can do beyond moving plants into a greenhouse or garage. Most plants will suffer enough damage to set back production by a few years. But, there are strategies we can use to at least keep the plant alive.
The first step in freeze protection is the initial site selection. All tropical and semitropical plants should be planted on the south side of a windbreak. This can be a fence, house, garage, shed or hedge. The windbreak will block much of the north wind and absorb heat throughout the day, releasing it during the night.
Tent the plant to trap heat and prevent radiation to a clear sky. This could be plastic, sheets, tarps, or blankets. You can also use large cardboard boxes, trash cans or build a frame of wood, covering it with cloth or plastic. Of course, wind is going to be a problem so anchor your tent with bricks, lumber, buckets of water, or stakes. When tenting, remember to use the covering like a tent. It should cover the plant with the ends dropping to the ground. It is not helpful to wrap the plant like a lollipop. This method does not take advantage of the radiant heat coming upward from the ground. The tent method will capture this heat and help you plant survive the freeze.
You can add additional protection by raking the mulch away from the plant. Bare ground absorbs the sun’s heat while mulch will deflect the heat. Another source of heat is lighting. Add strands of the old-style Christmas lights, the new twinkly ones will not add heat. A mechanics light, or bathroom heater will also work. Do be careful with these last two so you don’t awake to flames in the backyard.
When a big freeze is predicted, probably the last thing you think of is getting out to water the plants. Seems counter-intuitive but water can protect plants. Plants suffering from drought are less tolerant of cold and suffer injury at warmer temperatures than normal. Water plants several days ahead of cold weather. Secondly, water absorbs heat from the sun, stores it, then releases the warmth slowly. Watering before a freeze creates a source of warmth higher that the freezing point that will radiate through the night. This alone will not save your tree but used in conjunction with tenting you should have good results.
Another method is using large trash cans or 5-gallon buckets filled with water. Make sure the lid is on, this helps with radiation. If you have a grafted plant, place several buckets of water around the truck to protect the graft union. Along with tenting, this has proven to be a reliable method of saving the plant.
Another use of water is spray irrigation during the freeze. You have probably seen fruit growers using irrigation to protect crops from a frost or freeze. For the homeowner, this method seldom works and often make things worse. The plants must be showered with a water spray from before the freeze but during the freeze and well after the freeze. A homeowner’s irrigation system release too much water for this method. For homeowners, this results in a soggy, muddy lawn with drowned plants. The recovery is long and damaging.
Banking soil up the trunk of grafted trees is beneficial in saving tree grafts. Covering the graft union will act like insulator. You may lose the branches and leaves but the tree will regrow true to the scion you purchased. Be sure to use soil, not mulch or leaves. Only soil will provide the protection you need and aid in the radiant heat process. To use this method, spray the trunk with a fungicide first. Then bank soil all around the trunk and up beyond the graft union. You can do this in November or with the first predicted freeze and leave until March. After removing the soil bank from the trunk, spray again with a fungicide. Also, make sure to remove the soil from around the roots. Citrus roots are very shallow and will suffer if they become too deep.
Insulation is accomplished by using various objects to keep ice from forming in the cells of the woody parts of plants. The use of pipe insulation, sheets, Styrofoam or plastic give spotty results and simply do not work well. However, sheets of fiberglass insulation will work to protect from freezes. You will need to wrap the plants prior to the freeze and remove as soon as the freeze has passed. Otherwise the plant will overheat. It is helpful to cover the insulation with plastic to keep dry.
Whichever method you use, the devil is in the details. When it comes to freeze protection it’s all in the timing. A sudden 30-degree drop will cause severe damage no matter the precautions you take. A gradual cooling off may do no damage. But, if a spring crop is important, you should have a plan in mind for winter protection. Have your materials on hand and don’t wait until the “Nor’easter” is upon us…prepare as soon as it’s predicted.
Q: Have you seen this in your garden?
If you see this, you may have Aster Yellows in your garden. Aster Yellows has been showing up in gardens around the county. Click here to find out more about Aster Yellows and what to do if you have this on a plant in your yard.
A: Predictions are often incorrect so it is best to wait before harvesting all your citrus. Fruit freezes if the temperatures drops to 26-28 degrees for several hours. With temperatures of 32 you may have foliage damage but the fruit will be fine left on the tree. Learn more at https://aggie-horticulture.
A: The problem you see on your dwarf peach is woolly aphids. Woolly aphids are tenacious little creatures but can be treated effectively with low-impact methods of control. These aphids are a mixture eggs, larva, juvenile and adults. The good news is they have lost their wings and cannot fly away. Normally, we would suggest you leave them for nature to take care of but this is a huge infestation so it’s time to take measures to knock down their numbers.
The first action should be to take a cloth or simply put on a glove and wipe the majority off the limb and twigs. Secondly, use a strong blast of water to wash as many off as possible. Be sure to spray the trunk, limbs, twigs and under leaves. This should remove the majority of aphids. You can now decide to leave them to predators or take further action. If you decide to continue, you should use a horticulture oil such as Neem oil. Mix it as directed and follow the instructions on the bottle. The purpose of the oil is to smother the remaining aphids and any eggs that may hatch. Saturate under the leaves and in all the nooks and crannies of the trunk. Should they reappear, just repeat these steps. Most likely, some aphids will be able to overwinter on the plant so be prepared to use these methods in the spring.
Q: I looked out at my lawn this morning and saw this shiny, gauzy white web all over my trees? How can I remove it? Is it harmful?
A: Well, you are the lucky winner of the Bark lice Lottery. We have two types of bark lice in this area, Archipsocus nomas and Cerastipsocus venosus. Both are small soft bodied insects, rarely seen. They are often referred to as tree cattle because they herd together as they feed around the tree truck and limbs. They are rarely found on the foliage. Bark lice are a great clean-up crew feeding on fungi, bacteria, dead insects and lichens.
Although some think they are unsightly, they are highly beneficial and should be left alone. Eggs are laid under the protective web, the insect then goes through five to six instars. With the first fall frosts, the group will begin to decline, along with the web.
A: What you have on your leaves and fruit is black sooty mold. We have a number of people complaining of sooty mold this year because we had a cool, mild, wet winter followed by high heat and humidity. Perfect growing conditions.
Sooty molds are fungi growing and feeding on honeydew. Honeydew is produced by sap sucking insects feeding on your plant. These insects include white fly, scale, meaylbug, psyllids, aphids, just to name a few. It is important to deal with the insect as well as the sooty mold.
Sooty mold can be a real problem for plants by restricting the sun’s ability to penetrate to the leaf reducing the plant’s ability to perform photosynthesis. This reduces tree vigor and can result in leaf and fruit drop.
First step is to identify the insect. Should it be scale or aphids, look for fire ants at the bottom or near to the tree trunk. Fire ants will farm the insect in order to harvest and eat the honeydew. You must control both the sap sucking insect and the ants.
Non-chemical control of the insects will be difficult but not impossible. Do hit the foliage with a hard water spray early in the morning for several days and then several times a week thereafter. You can also use an insecticidal soap but only if you don’t see any beneficial insects such as lady bugs or predators such as lizards. A dormant oil can be used to suffocate the insects if the temperature is under 85 degrees.
Purchase a good fire ant poison and use as directed. Should you need to use a chemical for insect management, do read the label, make sure it includes control of the insect you are targeting, then use as instructed.
A: It appears you have Oak Leaf Blister. This is a fungal disease that attacks most all varieties of oak . Although the symptoms may begin after a cool, wet spring, most homeowners don’t notice the problem until leaves begin prematurely falling in late summer. New leaves may have blisters and lesions while older leaves just look dry and blistered.
A good regimen of fertilization and watering will enhance tree vigor throughout the year. It is useless to spray the tree unless you’ve had repeated years of symptoms. In this case, you can spray the tree with a dormant oil before bud break in early spring. Additionally, remove all fallen leaves and destroy to minimize reinfection. If this is not possible, mow the leaves repeatedly then add a nitrogen fertilizer to add in a quick breakdown.