Farm & Ranch
Neonicotinoid insecticides losing efficiency in potato psyllid control
By: Kay Ledbetter
AgriLife Research study shows biological control may help
Writer: Kay Ledbetter, 806-677-5608, skledbetter@ag.tamu.edu
Contact: Dr. Ada Szczepaniec, 806-354-5806, ada.szczepaniec@ag.tamu.edu
AMARILLO – The potato industry may be losing a mainstay in the battle against psyllids, according to a recent Texas A&M AgriLife Research study.
Dr. Ada Szczepaniec discusses her greenhouse study on potato psyllid resistance to neonicotinoid insecticides. (Texas A&M AgriLife photo by Kay Ledbetter)
Dr. Ada Szczepaniec, AgriLife Research entomologist in Amarillo, said while there may be varying degrees of resistance to neonicotinoid insecticides in populations of psyllids across Texas, her recent study indicates they’ve lost their punch.
“We are able to provide strong evidence that these insecticides no longer suppress populations of psyllids below desirable levels,” Szczepaniec said. “However, there may be some biological control measures to help in this ongoing battle against the potato psyllid.”
The potato psyllid is a tiny insect with sucking, piercing mouthparts that transmits a bacterium, Candidatus Liberibacter solanacearum or Lso, which causes a disease called zebra chip and can cause tremendous losses to producers, she said. Producers have used the neonicotinoid insecticides to protect their solanaceous crops, mostly potatoes, in the past.
Szczepaniec said the study, funded by the Texas Department of Agriculture, indicates applications of neonicotinoid insecticides at planting, which are a considerable cost for producers, should be replaced with investments in post-emergence applications of insecticides other than neonicotinoids.
Integrating predators in suppression of psyllids could also be considered, especially when incidence of Lso is low and the threat of zebra chip disease is decreased, she said. However, more research is needed before recommendations regarding biological control can be made.
Her study included colonies of the potato psyllid from all major potato-producing areas of Texas. These colonies were established and maintained in the greenhouse for at least two generations before experiments examining their resistance to neonicotinoid insecticides began.
“Over the course of a year and a half, we completed testing the majority of the populations of psyllids for resistance to imidacloprid and thiamethoxam,” Szczepaniec said.
Colonies of the potato psyllid from all major potato-producing areas of Texas were studied. (Texas A&M AgriLife photo by Kay Ledbetter)
Based on the Insecticide Resistance Action Committee definition of resistance, “heritable change in the sensitivity of a pest population that is reflected in the repeated failure of a product to achieve expected level of control,” the potato psyllid populations across Texas are resistant to both neonicotinoid insecticides, she said.
Szczepaniec conducted a second study to identify alternative biological controls. Surveys of all arthropods associated with three different potato types – a russet, a red and a chipping variety – were carried out at the AgriLife Research station near Bushland.
“While we have only one year of data to draw our conclusions, the survey has revealed trends in predator abundance that have important implications for potato production,” she said.
“First, potatoes harbor a relatively diverse group of predators, and minute pirate bugs in particular are associated with potatoes throughout the season,” Szczepaniec said. “This is important because they were identified as key predators of the potato psyllid and their presence is important to suppression of the psyllid.”
She said other predators included long-legged flies, which are generalist predators, lady beetles, spiders, parasitoid wasps and syrphid flies. Russet potatoes had the highest prevalence of predators.
Second, Szczepaniec said, it was important that minute pirate bugs were strongly correlated with thrips, which were also abundant in potatoes throughout the season. Minute pirate bugs are highly attracted to thrips, which are not key pests of potatoes.
“So, it appears that the secondary pests, thrips, may help support a resident population of minute pirate bugs that can suppress the primary pest, potato psyllid,” she said.
However, Szczepaniec did not encounter significant numbers of potato psyllids in the survey, thus the impact of these predators on psyllids could not be established. It is likely, though, that if minute pirate bugs are present, it would inhibit colonization and suppress numbers of the potato psyllid.
“When the cumulative numbers of predators were examined over the sampling period, we noted relatively high initial numbers of lady beetles and minute pirate bugs that decreased in abundance immediately following a broad-spectrum insecticide that was applied to suppress grasshoppers,” she said. “This trend is not surprising and it validates our decision to survey potatoes in a field at our research farm that is not subject to an intense insecticide management program.”
Szczepaniec said while a transient influx of generalist predators can have an impact on pest suppression, the persistent presence of resident populations of generalist predators is key to effective biological control.
“We know managing the potato psyllid and zebra chip disease will require a comprehensive and integrated approach going forward, and this research successfully establishes one class of insecticides as no longer effective in potato protection,” she said.
“Given the high incidence of the key psyllid predator, we believe integrating insecticide applications at lower intensity than weekly sprays with biological control releases may provide a viable option for psyllid suppression, especially when the proportion of psyllids transmitting the pathogen is very low,” Szczepaniec said.
She admitted that much research remains to be done in order to test the feasibility of this approach. The next most immediate research focus will be to identify if populations of psyllids across Texas are resistant to any other frequently used insecticides.
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Farm & Ranch
Tracks in the Sand
This morning, I walked out into my arena and noticed something that gave me pause. The roping steers had been in there the day before, and even though the ground was wide and level, the sand carried their story. Hoofprints crossed every direction, but in several spots, the same trail was pressed deeper than the rest. Twelve steers had been turned out, yet more than a few chose the exact same path, wearing it down until it stood out from all the other tracks.
Cattle are creatures of habit. Anyone who has spent time around them knows this. They like routine: the same feed, the same water trough, the same shade tree in the pasture. When they are turned loose, they rarely wander without purpose. More often than not, they move together, following the same course as the steer in front of them. There are reasons for this: efficiency, safety, instinct. Walking a beaten path conserves energy, and following the herd is their natural defense. Even in an arena with no real destination, those instincts come through. By the end of a short turnout, you will see the evidence, lines where they have chosen the easiest way to travel and stuck with it.
Out on the range, those lines last longer. Before fences and highways, cattle drives cut deep paths across the land. The Chisholm Trail, which carried herds north from Texas through Oklahoma into Kansas, was walked by millions of cattle in the late 1800s. More than a century later, faint traces of those trails remain, worn so deep by hooves and wagon wheels that the land still carries the mark. On ranches today, you can see the same effect in pastures where cattle walk the same lines between water and grazing. From the ground those trails might look like nothing more than dusty ruts, but from the air, they sometimes stand out as sharp lines winding through otherwise open fields. Cattle do not simply pass over the land; they shape it. Every step adds up.
That simple truth extends beyond livestock. We all make tracks. Our habits and routines are our trails, worn in by repetition, sometimes efficient, sometimes limiting. Like the cow paths, they can serve a purpose, keeping us steady and helping us move forward. But when repeated without thought, they risk becoming ruts, keeping us from stepping into new ground. History offers perspective here too. The old cattle trails built towns and economies, but once railroads and fences changed the landscape, those paths were no longer useful. Sticking to them would have meant going in circles. Progress required something new.
The Tracks We Leave
Standing in the arena, I thought about the kind of tracks I leave behind. Most of mine are not visible in the dirt. They are pressed into my daily life, how I work, the way I handle challenges, the example I set. Some are helpful and worth keeping. Others may have outlived their purpose. The difference comes in knowing when to stay in the track and when to step out of it.
Tomorrow I will drag the arena and smooth it all clean again. The next time the steers are turned in, they will make the same trails. That is their nature. But unlike them, I have a choice. I can decide which paths are worth walking, which ones to change, and what kind of tracks I want to leave for others who might follow.
Tracks tell a story. Sometimes they are only temporary, fading with the next rain. Other times they last for generations, reminders of where herds and people once walked. This morning, the cattle showed me again that even the smallest things on the ranch carry meaning. Their tracks in the arena were not just marks in the sand. They were a lesson: every step matters, and the paths we choose shape more than just the ground beneath our feet.
Farm & Ranch
Grazing North Texas – American Lotus
Farmers and ranchers are in a very close partnership with Mother Nature. If we really pay attention, she presents us some interesting scenarios.
For example, though they are totally different types of plants, water lilies and prickly pear have a lot in common. They both have strikingly beautiful flowers, both plants are edible, both of them are invaders into their respective habitats, and too much of either one can be an obstacle that we have to deal with.
Many north Texas ranches rely on excavated ponds for livestock water. Any time a pond contains a significant amount of shallow water so that sunlight reaches the bottom, some type of pond weed will develop. The plant family that includes water lilies and lotuses is a common invader in our livestock water.
Water lilies and lotuses are in the same plant family but they are two separate genera. There are easy ways to tell them apart:
• A primary difference is that water lily leaves commonly float on the surface, but lotus leaves can grow above the water line.
• Water lily leaves and flowers are thick and waxy, while lotus leaves and flowers are thin and papery.
• Water lily leaves have a distinct notch in the leaf, while lotus leaves are more rounded.
• Water lily flower petals are pointed, and lotus petals are more rounded.
The photos attached to this writing are from Clay County, and this plant is common across north Texas. American lotus is adapted to a wide area, from Honduras north through Mexico and across the eastern US and into Canada.
American lotus is a perennial, and it is cold tolerant and heat tolerant. It can grow in any pond or slow moving stream that contains shallow water areas. It prefers water with a depth of about 12 inches. Germination can occur from the large lotus seeds. Tubers, or roots, are established in the mud, and long slender stems extend upward. Leaves and flowers are both emergent in that they grow above the water line.
Lotus flowers are fragrant, and yellowish white with rich gold centers. They open in the morning and close by late afternoon, then open again the next day.
Lotus is an edible plant and has a history as a food source. The large tuberous roots, the size of a human arm, were baked like sweet potatoes. The leaves were eaten like spinach, and the large seeds were ground into flour. Stems taste somewhat like beets and were usually peeled before being eaten.
There is a large world-wide industry of cultivating lilies and lotuses in water gardens. According to Dr. Jerry Parsons, Professor and Extension Horticulturist with Texas A&M AgriLife Extension, cultivation of these plants dates back as early as ancient Egypt. Today, anyone with determination and a little money can have a water garden.
In 2011, the 82nd Texas Legislature designated the water lily “Texas Dawn” as the official Texas State Water Lily. Texas Dawn is a hybrid developed by Texas resident Kenneth Landon, a world-renowned expert in the field of water lilies and the director of the International Water Lily collection in San Angelo.
Ducks and other wildlife utilize the large acorn like seeds of American lotus, and submerged portions of all aquatic plants provide some form of wetland habitat. Many of us have tried to pull a bass out of a group of water lilies or lotuses, and I’m sure others have had better luck than I did. Although there can certainly be benefits to lilies, lotuses, and other aquatic plants, they can also infest ponds to the extent that the pond is not functioning correctly.
So, while the rest of the world works hard to grow these plants, ranchers sometimes need to control populations in their stock ponds. Once it gets a foot hold, American lotus can spread aggressively in wetland areas.
The primary issue that encourages American lotus, and most other water weeds, is shallow water. Look closely at a good livestock pond and you will find that the deeper water is basically free of infestation. Any pond will have a certain amount of shallow water that encourages water weed growth, depending upon the terrain at the pond site and how the pond was constructed. Some ranchers who enjoy and utilize wetland habitat may prefer to have ponds with significant shallow water area.
Almost all livestock ponds have a certain life expectancy. Siltation, or movement of soil into the pond bottom through rainfall runoff, is a natural occurrence. How fast siltation occurs into each pond, and how deep the pond was to start with, determines the length of time that the pond will contain adequate depth for dependable water for livestock.
Ponds that develop infestations of water weeds over a large percent of the surface may not have adequate depth to remain a viable water source for livestock during drought periods, especially in western north Texas where evaporation rates are higher.
Mud, or silt, from the pond bottom, can be removed to deepen the water, but this is a very expensive process. It is often more economical to construct a new pond rather than try to remove the silt from an old one. Most of us do not have the funds to continually construct deep water livestock ponds, so we must try to keep existing structures functioning and providing good drinking water for livestock, for as long as we can. Control of pond weeds like American lotus may be necessary, and it can be accomplished.
There is currently no feasible biological control. American lotus can be cut and removed, but this process us usually temporary because lotus can reestablish from seeds and roots.
American lotus can be safely controlled by chemicals. This must be done carefully. If a pond containing a large amount of any pond weeds is treated to remove all of the vegetation, a fish die-off could occur. When the dying weeds decompose, they use up the oxygen in the water and fish can suffocate. If possible, treat only a portion of the area, wait about two weeks, and treat another portion.
Farm & Ranch
The Many Benefits of Rabbit Manure
By Landon Moore
Rabbits offer a lot to the home gardener, and perhaps the most useful of all is their waste. Rabbit manure is likely the single most versatile and valuable fertilizer of any animal manure. It’s a “cold” manure, meaning it can be applied directly to plants in any form without the risk of burning them. In contrast, manure from sheep, horses, cows, and especially poultry must be aged before it’s applied, or it may damage plants. Because rabbit manure doesn’t need to be aged, it retains more of its nutrients and is therefore twice as rich as chicken manure and four times more potent than horse or cow manure. Rabbit manure is safe to apply to soil growing edible crops, has virtually no smell, and contains no harmful seeds. It can be used immediately, or be dried, powdered, made into tea, or turned into worm castings. A single trio of rabbits and their offspring can produce up to two cubic yards of fertilizer per year, along with 100 to 200 pounds of meat.
Rabbit manure is in such high demand as a fertilizer, particularly for roses, that it’s often sold online at a premium price. Some rabbitry owners even charge people to come scoop the manure themselves, paying by the bag. Larger rabbitries might sell by the truckload, but many owners keep it all for their own gardens. You may wonder what makes this little mammal’s excrement so uniquely useful. To understand, we first need to look at the qualities that make it special and then explore its various applications.
To begin with, let’s take a closer look at a rabbit’s biology. Contrary to popular belief, rabbits are not rodents but belong to the order Lagomorpha and family Leporidae, along with hares. All domestic rabbits are domesticated European rabbits (Oryctolagus cuniculus) and are unable to produce fertile offspring with American cottontails. Rabbits are considered “pseudo-ruminants” because they have a single-chambered stomach, but they also have an organ called the cecum, which functions similarly to a rumen and makes up about 40% of their digestive tract. They are crepuscular, meaning they are most active at dawn and dusk, typically feeding in the evening.
Rabbits actually produce two kinds of manure. The familiar dry pellets make up most of their waste, while the other type, known as “cecotropes,” is a moist and smelly substance resembling tiny bunches of grapes. Cecotropes are not fully digested, and because rabbits cannot chew their cud, they reingest the cecotropes as they are excreted. This fermented substance allows the rabbit to absorb more nutrients than it would through initial digestion. While cecotropes are occasionally found in cage trays, the feeding behavior that leads to them is usually only witnessed by the rabbit owner.
The dry pellets are the true manure that most people are familiar with. These small, round, dry pellets have almost no smell when kept dry. When crushed, they break down into a powder resembling tiny grass fragments because, in essence, that’s what they are. Some people crush the pellets before applying them to speed up their absorption into the soil, while others appreciate their “slow-release” feature. Additionally, the manure’s water solubility can be exploited in several ways. Soaking a wheelbarrow full of manure creates a potent sludge that can be easily applied to flat surfaces. If the odor is not an issue, the smell will dissipate once the manure is either dissolved by moisture or dried by the sun. Another method is to make manure tea: fill a cloth bag with manure, seal it, and submerge it in a barrel of water for a few weeks. A simpler method involves placing damp manure at the bottom of a barrel, filling it with water, and letting it sit in the sun for a couple of weeks. Stir occasionally, and you’ll have a powerful liquid fertilizer ready for use.
Domestic rabbits should be fed a modern, pelleted feed, which provides all the nutrients they require. This diet eliminates the risk of noxious seeds being present in the manure, making it safe to apply directly to the lawn, especially during winter. Winter and spring rains will break it down, and by late spring, you’ll have a healthy carpet of turf.
Rabbit manure’s nutrient content varies depending on factors like storage, age, and diet, but it generally contains around 2% nitrogen (N), 1.3% phosphorus (P), and 1.2% potassium (K). The Oregon Extension Service gives a range of 3-4.8% nitrogen, 1.5-2.8% phosphorus, and 1-1.3% potassium. Even at the lower end of the scale, rabbit manure has higher nitrogen content than poultry manure and twice the nitrogen content of cattle manure. One reason rabbit manure doesn’t burn plants is due to the biology of birds, which lack bladders and produce more ammonia in their waste. In contrast, rabbits release ammonia in their urine, which is why their manure may have a stronger odor.
Because of its balanced nitrogen-to-phosphorus ratio, rabbit manure promotes a wider variety of species in the same application area. Applying it directly to heavy clay soils will improve them quickly, especially when combined with other organic matter. It can also improve sandy soils by adding texture and helping them retain moisture. Anyone raising rabbits will have a steady supply of manure, as they are efficient producers. A small herd of 17 animals, including their litters, can produce about one ton of manure annually.
Beyond fertilizing, rabbit manure has several other uses. It is considered the best food for earthworms and can be combined with moisture-holding bedding like peat moss, shredded paper, or hay taken from used nestboxes. Many rabbitries (including my own) keep worm beds right under the cages. The resulting castings are rich in nutrients and can be used as-is or incorporated into soil amendments. A couple of feet of manure under a foot of soil in a hotbox can generate enough warmth to start and grow seeds, even in cold climates like Vermont.
In Europe and Asia, the rabbit meat industry is a billion-dollar market. While the Czech Republic leads in per capita consumption (over 8 pounds per person annually), China is the leading producer of rabbit meat. A recent study in China examined the effects of replacing peat moss in seed-starting soil with rabbit manure. The study found no significant difference in germination rates and noted that the manure provided increased nutrients for seedlings. The ideal ratios for seed-starting soil were found to be one-third manure, one-third perlite, and one-third vermiculite, or half manure and half perlite.
Rabbit manure is often overlooked as a nuisance, but as we can see, it’s an incredibly versatile soil conditioner, excellent fertilizer, ideal food for earthworms, and a superior seed-starting medium. Anyone raising rabbits should consider this another benefit, in addition to having a home meat supply, exhibition livestock, or pets.
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