Gall making insects in oak trees

Brownwood Bulletin
Scott Anderson

Have you ever wondered what makes those small balls that you see underneath leaves and stems of plants, such as trees?

According to Professor and Extension Urban Entomologist Dr. Mike Merchant, the growths, called galls, are often the result of insects laying eggs inside or feeding on the branches or leaves of trees and other plants.

The galls, Merchant said, were tumor-like growths that are produced by the plant in response to chemicals injected into the plant by adult or larval gall-making insect. The shape and size of the gall is determined by the precise chemicals that are used by each species of gall-maker. The mechanisms of gall formation and how these chemicals are used to make the galls are still poorly understood.

Most gall-making insects are tiny wasps that are in the plant-gall-making family called Cynipidae. Other common galls are also called gall midges. Some, like the hackberry nipple gallmaker, are relatives of leafhoppers called psyllids. Merchant said the most interesting fact is that each insect makes a distinctive and unique gall. It is unique enough that it is possible to identify the gall-maker by the type of gall it makes.

Gall formation usually takes place in the spring, when leaves and flowers and stems are rapidly growing.  Only during this time of rapid cell division and growth can these insects bend plant cell division to do their bidding.  Once a leaf or stem has stopped growing, these hormone-like chemicals can no longer affect the plant.

Merchant said the purpose for insect-induced galls seems to be to provide a sheltered feeding site for the gall-maker.  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.  The good news for the gardener or tree owner is that galls rarely cause much harm to plants.

Once a gall has formed on a plant, there is no need to kill the insect inside, as whatever energy loss will be suffered by the plant has already occurred.  In addition, short of ripping the galls off of the plant, there is no way to kill gall making insects inside their protective homes.

If there was a need to control galls on a tree, now would be the only time to do it. Sprays applied early in the spring could theoretically kill adult gall-making wasps or midges before they can inject their disfiguring drugs.  But little research has gone into this practice it is not advised, he said.

Instead, as you gaze on the swelling buds and rapidly greening trees in your backyard, just take a minute to consider the gall-making insect. In addition to all the other rituals of spring, these tiny creatures are working like crazy out there to provide little bug caves, or retreats, for their offspring.

Wooly aphids are also known to cause problems in oak trees as well. I am receiving calls concerning galls and aphids in oak trees here in Brown County. In order to get these problems under control it may take a combination approach of spraying the tree and using an appropriate systemic drench.

Is sorghum the next trendy pet food ingredient?

It’s no secret that consumer food purchasing trends have shifted in the past decades to sources they consider more “natural,” with terms like gluten-free, non-GMO and all-natural becoming marketing superstars.

Now, Americans are applying those same principles to their pets’ diets, and there’s potential for growth. Americans are predicted to spend more than $44 billion on pet food and treats in 2021.

With more than 100 million bushels of grain used to feed an estimated 183 million pet cats and dogs, sorghum is poised to take full advantage of market opportunities, according to John Duff, National Sorghum Producers executive vice president.

“While completely grain-free pet foods and pet foods excluding certain grains get all the headlines, the bigger trend in this market is toward natural, plant-based ingredients,” he wrote in a recent Southwest Farm Progress commentary. “And the reality is, there’s no better way to achieve these standards and meet companion animal nutritional requirements than with grains. Fortunately, if it’s an ancient grain, the demand is even higher, so sorghum is in the driver’s seat in many segments of the market.”

In fact, many consumers are shying away from grain-free pet food after the U.S. Food and Drug Administration began investigating reports of canine dilated cardiomyopathy in dogs eating grain-free diets.

Sorghum appears to have a lower glycemic index than other common grains used in pet foods, which is potentially beneficial to the fast-rising population of diabetic dogs.

Although it is still somewhat a niche market, sorghum is now available in more than 150 products from 15 pet food companies, according to the United Sorghum Checkoff Program. Since at least 2016, the sorghum checkoff has devoted funding to investigating sorghum as an ingredient in premium pet foods.

And pet foods are an avenue sorghum farmers can pursue as they work to sell products higher up the value chain, Duff noted. All markets move toward commoditization over time, he said, but farmers can capture higher value because consumers place higher value on the product. This gives farmers the opportunity to move away from commodity production toward specialty production over time.

“From regional differences to quality characteristics to sustainability, farmers interested in supplying [sorghum for pet food] can go as far into the weeds as they desire,” Duff said. “Or they can stay at a high level and concentrate on providing a consistent supply to the many volume-based producers. It’s their choice, but as with companion animals themselves, there’s something for everyone.”