Is it possible to treat potatoes against the Colorado potato beetle during flowering?

The potato's chequered history in Russia spans nearly 300 years, and for nearly two-thirds of that time, this crop has enjoyed a well-deserved popularity among the people. Easy to grow and adaptable to a variety of climates, the potato has earned the title of "second bread."

Even an inexperienced farmer who has planted this root vegetable in their plot and has some understanding of watering and hilling techniques can reap a decent harvest by the end of the season, if not for one "but." The Colorado potato beetle, that insatiable invader that penetrated the western Soviet Union in the 1940s, had become firmly associated with potatoes in the minds of residents across the country by 2000.

The importance of the Colorado potato beetle for potato farms

Many summer residents who are unable to reside permanently on their plots throughout the summer have encountered the following situation at least once in their gardening practice. The planted potatoes are growing well, the initial hilling has been completed, the humid summer doesn't require frequent watering, but some circumstance (such as a long-awaited vacation) prevents the landowner from visiting their plot for a week or two. Upon returning to their dacha, the owner discovers a ruined potato plot, consisting of bare stems completely eaten away by beetles. The harvest from the field is minimal and doesn't even compensate for the losses incurred on the purchased planting material. This situation is especially common in the southern regions of the country, where humidity is low and average summer temperatures are high. In the warm, arid climate of Central Asia, the Colorado potato beetle produces four generations per year, and in particularly hot weather, mass flights of adult beetles are observed, traveling up to several kilometers downwind at speeds of up to 8 km/h. Unable to find potato plantations along the way, the beetle feeds on wild nightshades, including poisonous black nightshade and henbane, until it reaches a newly cultivated field. It's no surprise that by now this vicious pest has conquered the entire world, except England, where a strict quarantine is in place, and Antarctica.

The Colorado potato beetle typically does not feed on potato tubers themselves, either as an adult or as a larval insect. These insects can be found on potato roots only in early spring, when overwintering hungry adults locate tubers ready for planting by scent and recuperate until the first shoots emerge. Although this insect species evolved in the deserts of Mexico's Sonoran Province, where the beetles fed on wild plants of the nightshade family, today the Colorado potato beetle's primary and favorite food is green potato tops. However, on vegetable gardening forums, users often claim that when potato, eggplant, and pepper crops are planted nearby, the beetle prefers the more tender shoots of the latter two crops, and only after the pepper leaf pulp has been destroyed does it switch to feeding on potato tops. This situation is likely due to the spread of modern potato varieties with tough, hairy, or bitter foliage (due to glucosides), which are more resistant to pests. These include, for example, 'Nikulinsky,' 'Bryansky Nadezhdy,' 'Kamensky,' 'Shurminsky-2,' 'Sulev,' 'Temp,' 'Olev,' 'Svitanok Kievsky,' 'Mysl,' 'Lasunok,' 'Utro Ranneye,' and others.

The most dangerous pest for potato crops are the Colorado potato beetle larvae. Although each immature beetle consumes no more than 30 milligrams of leaf pulp per day, the pest's mass production and the ability of adults to produce several generations per season can lead to the destruction of 40 percent of the potato crop. The mass production of egg masses and, consequently, the larval population, the voracious appetite of both young and adult beetles, their adaptability to frost and drought, their resistance to many poisons, and their rapid tolerance to insecticides have elevated the Colorado potato beetle to the top of the list of potato enemies.

Therefore, unfortunately, it is not possible to ignore this pest in your potato farm.

Scientists are closely studying the life cycle of the striped leaf beetle, chemists and geneticists are synthesizing new insecticides, and farmers and gardeners are testing out old folk remedies. While a universal and completely safe panacea for the Colorado potato beetle has yet to be discovered, many vegetable growers have fairly effective methods of controlling it, and gardening stores offer a variety of strong and relatively harmless chemicals. Today, for many, the pressing question is not finding a way to combat this voracious pest, but rather— Is it possible to treat potatoes against beetles during flowering? Let's try to figure it out.

The importance of potato flowering for tuber maturation

Although only the tubers of the potato have the primary nutritional and industrial value, the plant must complete a full vegetative cycle to properly develop these structures. Photosynthesis, a key process in plant metabolism, occurs in the green, above-ground portion of the plant exposed to sunlight. Photosynthesis involves synthesizing simple inorganic compounds first into monosaccharides (glucose molecules), and then into complex polysaccharides, including the coveted starch. Starch polymers accumulate in the potato's storage organs—the root tubers.

The number and size of tubers depend on the quality and duration of photosynthesis, the sufficiency of starting materials, and the presence of general favorable factors (heat, light, humidity, soil air, and underground space). This explains why damage to the green mass by the Colorado potato beetle affects the root crop yield. Having grown green mass and developed reproductive organs, the potato plant begins to store nutrients "for future use." Tuber emergence and formation in mid-early potato varieties popular in Russia occurs during flowering, which coincides with the period of greatest activity of adult insects and their larvae.

Beetles feeding on the tops during this crucial time for plants inhibits tuber formation, as synthesized nutrients are used to repair damaged organs rather than being stored underground. Furthermore, fungal spores and viruses can enter the wounds during stem injury, leading to crop damage and contamination of the area. The importance of flowering for the potato harvest is indirectly confirmed by the fact that removing flowering heads, a practice some gardeners employ, can increase the number of tubers by one or two, but the resulting roots themselves are small, uneven, and low in starch.

An exception are some modern potato varieties, for which absence of flowering or a small number of flowers per cluster is the norm. These include the ultra-early varieties 'Rocco,' 'Timo,' 'Empress,' and 'Mariella.' The 'Vesna' variety produces buds only in wet summers and fades very quickly, and during periods of drought, it does not bloom at all. Eliminating flowering in this case is beneficial for the farmer, as the plant does not waste energy on the formation of organs that have no economic value.

Is it possible to spray potatoes against the Colorado potato beetle during flowering?

Many gardeners and a large percentage of entrepreneurs who grow potatoes for commercial use insecticides at any time during the growing season. Killing beetles with powerful new-generation chemicals always results in the preservation of the above-ground parts of the plants and, consequently, an increased yield. However, it is well known that synthetic chemicals accumulate especially heavily in potato tubers during flowering. Incidentally, there is considerable debate about the advisability of using industrial poisons during other periods of the plant's life cycle, as these substances tend to accumulate in the soil, interact harmfully with beneficial soil microflora and fauna, and be absorbed by subsequent generations of crops.

The scales of this debate, which expresses a negative attitude toward treating potatoes during flowering, can also be weighed against the beetle's lightning-fast adaptation to all new chemicals. It's enough to recall the now-banned insecticide DDT (trade name "Dust"), which caused a stir in the USSR in the 1950s. It initially successfully controlled the Colorado potato beetle and other agricultural pests, but later lost its effect. The key to the potato beetle's resistance and rapid tolerance to poisons is a genetically determined mechanism for eliminating plant alkaloids from the body. The Colorado potato beetle's diet in its historical Mexican range consisted of toxic nightshades, which are deadly to most other herbivorous insects.

The beetle's metabolic system is adapted not only to recognize and eliminate hazardous substances but also to accumulate harmful compounds in tissues. This metabolic mechanism renders the host inedible to most predators, as indicated by the bright warning coloration of adults, larvae, and eggs. The only exception among toxic substances are modern systemic pesticides (such as Confidor Maxi Extra). These insecticides penetrate the plant through the roots and accumulate in all its organs. Insects ingest the poison by feeding on the poisoned plant parts and die. Unfortunately, many systemic insecticides linger in the soil for up to 10 weeks and can harm humans through contact with or consumption of treated plants, as well as destroying helper insects, fish, and pets. The toxicity of chemicals to bees, predatory insects, and beneficial amphibians is another important reason why treating potatoes with pesticides during flowering is highly discouraged.

The dramatic acceleration of development in environmental science, microbiology, and nanotechnology in recent years has led to the emergence of an unprecedented field in the chemical industry: the production of biological insecticides. The active ingredients in these preparations are microorganisms—natural pests of the Colorado potato beetle (certain strains of fungi and bacteria)—and entomopathogenic nematodes.

Fungal insecticides (avermectins) produce neurotoxins that paralyze and kill insects. Furthermore, conidia of some microscopic fungi can penetrate the insect's body and infect its organs, causing death. Avermectins are sensitive to humidity, temperature, and light conditions, require refrigeration and dark storage, and should be applied after fine misting in the evening.

Bacterial pathogens are isolated from strains of soil microorganisms and affect insect pests through the intestinal tract by producing toxins. These products are available as dry powders, have a shelf life of up to eighteen months under normal conditions, and, unlike fungal insecticides, are virtually non-allergenic.

Insecticides based on EPN (entomopathogenic nematodes) are the most promising and effective fourth-generation products. These microscopic worms enter the bodies of adult insects and larvae through food and infect their hosts with symbiotic bacteria that produce a toxin. Nematodes are sensitive to dryness; EPN treatments should be carried out after fine misting in the evening.

As numerous studies show, insecticides based on natural microbes are non-phytotoxic, pose virtually no harm to humans, bees, fish, and warm-blooded animals, are quickly inactivated in the natural environment, do not accumulate in soil or tissue, and often have a narrowly targeted effect. Most importantly, they do not cause tolerance in the target pest. Despite their higher cost, these products are being actively studied and may eventually replace synthetic analogues. However, their impact on human and beneficial animal health, as well as the full range of ecological relationships between these microorganisms, has not been fully studied, so it is advisable to observe preventative precautions when working with them.

Safe methods for treating potatoes against the Colorado potato beetle during flowering

As we've already established, spraying potatoes with chemicals during flowering to control the Colorado potato beetle is unsafe for human and livestock health and has detrimental consequences for the overall ecosystem. Let's now consider safer methods of controlling the Colorado potato beetle that can be used during this growing season.

•    First of all, the bioinsecticides mentioned in the previous chapter will help get rid of pests. Fungal preparations such as AvertinN and Aversectin C, which are effective against Colorado potato beetle larvae, bacterial preparations such as Bitoxibacillin and Fitoverm, and the nematode preparation Nemabakt have shown good results on potatoes. Agravertin, Akarin, and Bikol are also popular among farmers. Garden centers stock bioinsecticides such as "No Colorado Beetle!", "Aktofit," "Boverin," and "Aktarofit." It's important to remember that all biological insecticides and their toxins degrade very quickly in the environment and have a delayed effect. If the previous generation of Colorado potato beetle larvae is not completely destroyed and mature individuals remain on the crop, new sprayings will be necessary during and after flowering. Before using any product, carefully read the instructions and strictly follow the recommended usage. The number of repeat treatments and the final effect depend greatly on climate conditions, the overall condition of the plants, and the timing of application, and can vary significantly among users.
•       Mechanical collection of insects is practical on small plantations. It's important to remember the specific defensive behavior of adults: when threatened, they don't fly away, but fall to the ground, feigning death. If a hidden beetle is unnoticed, it will reappear on the plant within a few minutes. Gardeners recommend the following method. Collecting the pests should be done by two people. The person in front brushes the adults with a long-handled broom into a wide net placed under the bush. The person behind them collects the larvae and eggs by hand. Mechanical collection of beetles is quite tedious, but after a few family outings, it can save this year's potatoes from damage and the farmers from a crop failure.
•         Folk wisdom suggests how to spray potatoes during flowering. Dusting with wood ash, especially birch ash, or irrigating with an ash-soap solution will not only kill the beetle but also provide the plants with natural potassium, which will increase yield. Sprinkle the potatoes after morning or evening dew or after rain, at intervals of two weeks. Diluting the ash in soapy water (30 g ash and 3-5 g laundry soap per 1 liter of water) will make the solution more adhesive and allow the product to adhere better to the leaves, including the undersides where the eggs are laid and the first generation of larvae live. Don't forget to sprinkle the soil under the plants. Ash consumption is high – about 10 kg per 100 square meters. You can spray potatoes during flowering to control Colorado potato beetles with a tar solution (100-150 g of birch tar per 10 liters of water). Tar is a concentrated byproduct of birch ash processing and is even more effective than the original raw material.
•    You can kill beetles during potato bloom with an infusion of onion peels. Pour about 0.5 kg of peels into a bucket with boiling water and let it steep for 2 days. Then, add soap to the undiluted infusion and sprinkle the potatoes on all sides. Adult beetles dislike the smell of rotting onions, and their numbers will decrease in the area.
•    Care should be taken when irrigating potato plants with infusions and decoctions of fragrant plants such as basil, calendula, and currant. Garlic infusion is also helpful. It's clear why you shouldn't use homemade preparations from poisonous plants to kill Colorado potato beetles during potato flowering. Alkaloids obtained from other common remedies, such as hemlock, bedbugs, wormwood, tansy, celandine, and the like, will penetrate the developing tubers and reduce their flavor or make them unfit for consumption. Try boiling 100 g of dried hot pepper in 10 liters of water for 2 hours, then adding 50 g of soap to the cooled mixture.
•    Beetles on potatoes during flowering can be successfully poisoned with a nicotine infusion (0.5 kg of tobacco per 10 liters of water should be infused for a day and laundry soap should be added before use).
•    Dusting with corn flour is also considered a good way to control potato leaf beetles. Corn flour, when consumed by larvae or adults, swells from the moisture in the insect's intestinal tract, damaging its internal organs.
•    Grazing certain poultry breeds on potato plantations unexpectedly yields good results. If Faverolles chickens are fed grated potato tubers and some chopped potato tops in their green feed starting at 20 days of age, and then at one month of age, 0.5 adult beetles are added, gradually increasing the dose. At three months, the hungry youngsters can be released into the potato plot. Unfed guinea fowl eat the pests even without training. Turkeys also cope well with the beetle, but unlike chickens and guinea fowl, these large birds can damage the plants themselves. To use poultry as a pest control agent, additional potato treatments should be avoided entirely. The only acceptable treatment is dusting with cornmeal. Furthermore, it's best to trim the flight feathers of guinea fowl and turkeys, as they can cause damage to the plants. These birds have not completely lost the ability to fly, and it is reasonable to fence off the potato field.
•    Starlings, shrews, and moles readily feed on Colorado potato beetles. These animals should not be discouraged from the garden.

Rules for spraying potatoes during flowering

How to treat potatoes against Colorado potato beetles during flowering is up to you. We strongly recommend using natural methods of controlling potato leaf beetles that are gentler on plants, the environment, and humans. Let's summarize our recommendations for treatment techniques using plant-based and biological insecticides.

•         Many active ingredients contained in herbal decoctions and infusions are inactivated by sunlight. Therefore, prepared solutions should be used promptly, preferably in the evening, close to sunset. This also eliminates the risk of sunburn due to the lens-forming properties of moisture droplets.
•         Use laundry soap as an adhesive.
•         Alternate products to avoid insects becoming accustomed to one type of active substance.
•         If possible, use personal protective equipment, wash your hands and face after treatment, and keep children and pets away from the plantation.
•         Strictly follow the instructions and dosage on biopreparations.

If treating your potatoes with chemicals during flowering to control Colorado potato beetles doesn't worry you, we recommend familiarizing yourself with the rules for doing so:

•         Use factory sprayers.
•         Do not neglect protective clothing, gloves and a respirator.
•         Keep bystanders, especially children and pets, away from the field.
•         It is extremely dangerous to your health to smoke, drink or eat during the procedure.
•         Working solutions cannot be stored for more than 24 hours.
•         It is better to treat plants early in the morning, in the evening at sunset, or in cloudy, but not rainy, weather to avoid sunburn on the leaves.
•         Wind and rain occurring within 24 hours of the end of pollination will reduce the effectiveness of the work.
•         Tubers harvested 40–60 days after the last treatment (depending on the preparation) are suitable for food.

Potato growers' forums demonstrate how pressing the question of whether it's possible to kill Colorado potato beetles during potato bloom is for our compatriots. The temptation to quickly and reliably solve the problem with potent pesticides is met with strong resistance from common sense, not only among small gardeners but also among larger landowners.

https://youtu.be/khyBiT5st2s

"This beast easily adapts to poisons, produces an antidote, and inherits the ability to produce it. It also loves nitrogen fertilizers, which our gardeners can't live without shoveling into the soil. Grow your vegetables organically, and your potatoes will grow such tough tops that no beetle can chew through... yes, chicken manure is also useful, but only after harvesting."

 

"No, you can't. I have the same situation at my dacha—some of my potatoes are blooming, while others aren't. I selectively spray them, only on the non-blooming ones. Although it's not very convenient and takes a lot of time.

It is believed that at this time tubers are forming, therefore, it is impossible to spray potatoes."

 

"During flowering, I prefer to pick them every day, and before flowering, you can spray them. But after flowering, I don't do anything, since the tubers are already formed and the beetles are not a problem."