oak

The asps are out! It’s been years since we’ve had a big asp outbreak. These stinging hump back caterpillars love oak trees, yaupons hollies, burford hollies, hawthorns, altheas, and hibiscus. I saw a fresh hatching no bigger than a pea on some hollies the other day. Take a close look at your plants and see if you find any skeletonized leaves. Spray thoroughly on the tops and bottoms of the leaves with Spinosad, or Liquid Sevin as a contact kill. Thuricide can also be used, but the caterpillar has to ingest the leaves to be killed and that takes a couple of days.

Leafcutter bees are also a problem now. These bees are generally passive and not very aggressive. However they can sting and will do so if handled or aggravated. You usually never see the bee, but you do see the damage left behind. They cut perfect semi-circles out of the leaves of soft tissued plants such as crape myrtles, hibiscus, plumbago and roses. We first noticed the damage on our kapok trees. They take the leaves and roll them into perfect tubes to block their nest openings. No treatment is necessary since the nesting period of the female is usually just a couple of weeks. The scalloping of the leaves will not kill your plants, it just leaves them unsightly to some. These bees are great pollinators, so I say, “let them do their thing”.

-DeAnna

Folks have been bringing in oak leaves with lumps, bumps, and fuzzies, wanting to know, what is this and what do I do about it? Several different insects can cause galls, but predominantly it is different species of small wasps. I collected these three most common types of oak leaf galls off just one branch of my tree. The wasp flies in and lays eggs on the leaf or stem, in a fresh and growing portion of the tree. When the larva emerges from the egg, it starts secreting a chemical that causes the oak to grow abnormal tissue in which the larva shelters and feeds. It is usually just a cosmetic issue, not a threat to tree health, and other than the stem galls, other galls fall away as the leaves drop, with seemingly little carryover from one year to the next. Insecticide treatments are not recommended in home landscapes, only in commercial oak nurseries where the trees are relatively small and in dense blocks, and aesthetics are paramount to salability. Factoid- in medieval times, ink was made by crushing oak galls to release tannic and gallic acids, in which iron scraps were dissolved, the resulting mess, after filtering, and gum arabic added, making black ink. This was the standard writing ink for over 1400 years, and is still manufactured for use by some artists.

–James

Oak Tree Caterpillars

Be on the look-out for oak tree caterpillars in your oak trees. They cluster together in large groups feeding on the leaves of your trees or you may notice poop under your tree (on your patio or walk.) They can be killed with Thuricide sprayed onto the leaves or with Spinosad. If your trees are too large to spray or you just don’t want to, they will not kill your trees. The tree will leaf back out in the Spring. I have had customers say that early in the mornings they could hear them chewing the hard oak leaves. Crunch, Crunch, Crunch!

Powdery Mildew on Mesquite Trees

With the cooler temperatures, shorter days and rains in the past few weeks, powdery mildew fungus has attacked mesquite trees. Since the trees are getting ready to drop their leaves for the winter, it is not necessary to spray them. They will leaf out and be fine next spring.

-DeAnna

All from a shiny reddish ball. Or a fuzzy white ball. Or a corky brown ball. I’m talking oak galls, which commonly strike terror into the hearts of live oak tree owners this time of year. They are all caused by various species of small, stingless, solitary wasps. These wasps insert an egg (or several) into the tissue of small oak branches or young leaves, and are thought to modify the DNA of the plant, forcing the plant to produce growth (the gall) that supplies both housing and food to the wasp larvae living inside. The saliva of the wasp applied at the time of the egg laying is thought to contain a virus that produces the genetic changes, so wasp larvae have been eating GMO’s for millions of years.

So wasps are defacing and eating your oak tree this summer, what you gonna do about it? As one writer says, “I recommend a cold drink, a good book and a comfortable chair.” ‘Cuz there’s nothing you can do or should do about it. Oak galls come in periodic waves, a few one year, more the next, and none the year after. Or close thereabouts. This is thought to be due variously to the tree buildup up of tannins to discourage the gall formers, and to a buildup of parasitic wasps (also stingless) that drill into the galls and lay their eggs on the gall inhabitant. Crazy Mother Nature, there are even wasps that lay their eggs on wasp larvae that are consuming the original gall wasp larvae (did I put one too many eaters of larvae in there, I must proofread). The galls do not do substantial damage to your trees, and there’s really no way to get involved in the crazy gladiator’s pit of nature without screwing things up, SO DON’T SPRAY, just sit back in awe (or take a nap). And empty oak galls actually take in desirable boarders such as lacewing larvae and small spiders, scavenger ants and more beneficial wasps, all feeding on caterpillars and aphids.

Other fascinating factoids –

Oak galls were an important source of dark and permanent ink used for writing for over 12 centuries, and iron gall ink is still used by artists today.

Oak galls have recognized medicinal uses due to the high tannin content (and also used for tanning).

Before his landmark work on human sexuality, Alfred Kinsey was known for his study of gall wasps.

James

There are almost never seedlings growing from acorns. If there were, you would be able to pull them up easily. What you see are sprouts from the roots of the existing tree; therefore, you do not want to spray a herbicide on them in an attempt to eliminate the sprouts for you will hurt the “mother” tree along with the sprouts.

Only a small percentage of oaks send up suckers from the roots. It is a genetic trait, like freckles, except I like freckles. But like freckles and sunshine, some trees have the ability to sucker, but do not unless stimulated to do so. Oaks having a slight tendency to sprout suckers will often do so when roots hit a barrier, such as trees confined to a parking lot planter, or between a sidewalk and driveway. Also, when roots are disturbed and damaged by rototilling, they are more likely to sprout suckers. But some trees never will make suckers. When choosing an oak in a garden center, if there are sprouts coming up at the inside edges of the container, I would avoid that tree.

You may choose to mow them along with the grass, if grass still exists. Or if the grass has thinned too much, you might plant Asiatic Jasmine groundcover, and use hedge trimmers to trim the jasmine and oak sprouts to a uniform height. You can cover the area of sprouts with a heavy gauge woven geotextile, and then either mulch or spread large gravel or decomposed granite over the top of the geotextile. My favorite solution, when appropriate, is to cover the ground with geotextile and then build a wood deck.

Or if you prefer a thick green lawn, you may remove the oak tree, and all of the tree roots with a backhoe. If you just cut down the tree, grind down the stump and all the large roots you can see, there will still be thousands of oak sprouts emerging from the remaining roots in your new lawn or bed area for a few years afterwards. The area will need to be continually sprayed with an herbicide.

James

Oak Tree Caterpillars

Be on the look-out for oak tree caterpillars in your oak trees. They cluster together in large groups feeding on the leaves of your trees or you may notice poop under your tree (on your patio or walk.) They can be killed with Thuricide sprayed onto the leaves or with Fertilome Borer, Bagworm, Tent Caterpillar Spray containing Spinosad. If your trees are too large to spray or you just don’t want to, they will not kill your trees. The tree will leaf back out in the spring. I have had customers say that early in the mornings they could hear them chewing the hard oak leaves. Crunch, Crunch, Crunch!

Pansy Time

Pansies love the cool days of fall and winter. Plant them in full sun. Use Hi-Yield Blood Meal at the time of planting for larger and more profuse blooms. Once they become established use Maestro Rose Glo to keep them blooming throughout the season. You can also plant their dwarf counterpart violas. They have smaller leaves and blooms, but tolerate heat and moisture better.

Powdery Mildew on Mesquite Trees

With the cooler temperatures, shorter days and heavy rains in the past few weeks, powdery mildew fungus has attacked mesquite trees. Since the trees are getting ready to drop their leaves for the winter, it is not necessary to spray them. They will leaf out and be fine next Spring.

Rust on Plumeria

Plumeria are suffering from rust fungus caused by the same weather conditions. The undersides of the leaves have yellow- orange or reddish brown pustules. Since you should be withholding water from the plumeria so they can go dormant for the winter, be sure to gather up the leaves as they drop and discard in the trash. It is not necessary to spray unless the condition re-occurs in the spring.

Oak Tree Caterpillars

Be on the look-out for oak tree caterpillars in your oak trees. They cluster together in large groups feeding on the leaves of your trees or you may notice poop under your tree (on your patio or walk.) They can be killed with Thuricide sprayed onto the leaves or with Spinosad. If your trees are too large to spray or you just don’t want to, they will not kill your trees. The tree will leaf back out in the Spring. I have had customers say that early in the mornings they could hear them chewing the hard oak leaves. Crunch, Crunch, Crunch!

(Photo)

-DeAnna

About this time of year, every year, we visit our Texas plant growers. This year we took them Girl Scout Thin Mint cookies, as a thank you for shipping us their best grade A plants!

While at the growing grounds we drive the fields with our sales rep, looking at new plant varieties and new sizes of plants being grown. We even have a coding system to remind us which plants are the best for early spring shipment.

For the first time in 40 years, this year James and I saw robots spacing plants out in the fields. They say robots are a little better at spacing than humans. I’m not sure about that; here they are in action!

Below are photos of our visit last week.