The return on investment in the agricultural business, one of the most unpredictable, depends on many factors. But some risks are manageable; for example, every farmer can protect crops from weeds.
A professionally developed weed control strategy guarantees the producer a decent harvest and protects him from additional losses. The main thing is to act promptly and competently.
Name them – legion
Potatoes are grown in a wide-row manner, therefore, from the moment they emerge until the rows close, they have low competitiveness with weeds. Without taking serious measures to control weeds, it is almost impossible to obtain a harvest of marketable tubers in our time.
According to the head of the plant protection department of the branch of the Federal State Budgetary Institution "Rosselkhoztsentr" in the Astrakhan region Lyudmila Kostyagina, the species composition of weeds on potato plantings is diverse and represented by several groups. Young weeds include, for example, early spring ones: weed sunflower, white pigweed. Among the late spring plants, we can distinguish blue bristle grass and common barnyard grass. Perennial weeds are represented by root shoots - field bindweed, Tartary lettuce, field thistle, as well as rhizomatous - common reed.
Candidate of Agricultural Sciences, Deputy Head of the Branch of the Federal State Budgetary Institution "Rosselkhoztsentr" in the Bryansk Region Nikolay Rozhnov states that almost all weeds typical of central Russia are found in the region. The most common species here are: thistle, chickweed, common pickleweed, and chicken millet. The composition of weeds in the fields is relatively constant; minor changes are provided by previous crops in the crop rotation.
Russian potato growers have long developed technologies for the destruction of weeds, the effectiveness of which reaches 98-100%. But recently, farmers are experiencing serious difficulties in getting rid of black nightshade. This plant, like potatoes, belongs to the nightshade family. Being close relatives, they have the same resistance to most herbicides. Because of this, it is extremely difficult to effectively influence the weed without causing harm to the crop itself.
In addition, nightshade shoots appear much later than other weeds, when all agrotechnical and chemical methods have already been used. It has a developed root system, is capable of reaching 1-1,5 meters in height and competes with potatoes for nutrients and sunlight.
Unfriendly «neighbours"
According to the deputy head of the branch of the Federal State Budgetary Institution "Rosselkhoztsentr" in the Krasnoyarsk Territory Elena Vasilieva, the influence of weeds on crops is dangerous to underestimate. Unwanted vegetation takes moisture and nutrients from the soil, causing potatoes to receive insufficient nutrients for optimal growth and development. With high weed infestation, cultivated plants can be smothered at the seedling stage, which negatively affects photosynthesis and the formation of their green mass. All this subsequently leads to large crop losses.
Lyudmila Kostyagina emphasizes that weeds in potatoes reduce its yield, losses can reach 20-25%. There is also a negative impact on the size of the tubers. As a result, the level of marketability falls, the process of mechanized harvesting becomes more complicated, and the financial losses of farmers increase.
Weed control is also of great importance due to the fact that among them there are hosts of pathogens of a number of diseases. Candidate of Biological Sciences, Head of the Department of Potato and Vegetable Diseases of the All-Russian Research Institute of Phytopathology Maria Kuznetsova states that weeds are reservoirs of diseases of fungal, oomycete, bacterial and viral etiology. The dominance of vegetation in the fields, affected by the same pathogens as potatoes, contributes to the progressive accumulation of infection in the soil.
For example, black nightshade is affected by the pathogens anthracnose, alternaria, late blight and potato blackleg. Shepherd's purse and field violet serve as reserves for the tobacco rattle virus, which causes rusting of tubers. And field bindweed is a phytoplasma, manifested in the form of a red-topped crop.
Maria Kuznetsova draws attention to the fact that weeds can change the microclimate in crop plantings, which are less ventilated due to thickening. As a result, favorable conditions are created for the development of late blight.
Dangerous “neighbors” of cultivated plants also act as reservoirs of pests that carry diseases and viruses. First of all, aphids and leafhoppers. The spread of black nightshade, odorless chamomile, upturned acorn, dandelion and spreading quinoa contributes to the active development of stem nematode, which deteriorates the quality of tubers.
Errors in protection
One of the most effective methods of weed control is the use of chemical pesticides. Elena Vasilieva notes that competent selection of the active ingredient of the drug, together with compliance with the conditions and standards of use, can reduce the number and negative impact of weeds on potatoes.
According to Bayer Crop Science CIS Market Development Project Manager Konstantin Onatsky, the main herbicides that are presented on the Russian market today have been well known for more than 30-40 years. These drugs still remain effective when used correctly.
Unfortunately, not everyone is able to work correctly: not every Russian farm has a highly qualified agronomist, and not all farmers have a suitable education.
According to the observations of the head of the plant protection department of the branch of the Federal State Budgetary Institution "Rosselkhoztsentr" in the Krasnoyarsk Territory Maria Grishaeva, the use of herbicides without taking into account the species composition of weeds and thoughtful rotation of active substances entails “empty” economic costs, and very significant ones.
What other mistakes do farmers make when trying to control weeds on their own? Specialists from the Federal State Budgetary Institution "Rosselkhoztsentr" identify several of the most common mistakes. Agricultural producers often do not comply with the timing of the use of herbicides and violate the recommended consumption rates for preparations and working fluids. There are also those who use unauthorized drugs and incompatible tank mixtures. Many people do not take into account the current state of the plants and carry out treatments on weakened plants, for example, those damaged by frost.
Konstantin Onatsky refers to the most common omissions as the low rate of consumption of working fluid during treatments. According to the expert, when using any soil herbicide for pre-emergence treatment, you need to use at least 300 liters of working solution water per hectare. This is necessary so that the drug binds to the soil as much as possible, the weeds germinate faster and die immediately. In hot regions where drought is possible, after applying the herbicide, watering is necessary to improve its effect.
Representatives of the Federal State Budgetary Institution "Rosselkhoztsentr" note that today in all regions of Russia the practice of conducting monitoring, counting the number and determining the species composition of weeds is widespread. Farmers can familiarize themselves with crop inspection reports containing a list of the most common weeds. If the threshold of harmful infestation is exceeded, experts give agricultural producers recommendations on how to treat the area with herbicides. What is especially important is that farmers receive information about pesticides and agrochemicals approved for use in Russia. And this allows you to avoid irreparable consequences both for the manufacturer himself and for consumers of his products.
"Gold standard"
To the main trends in getting rid of weeds Konstantin Onatsky refers to the use of original soil herbicides based on metribuzin or aclonifen. The choice depends on whether the potato varieties are resistant to metribuzin/prometrin.
The expert notes that there is also a combined, or double, application regimen, when part of the drug based on metribuzin is administered before germination in a dosage of 0,6 to 0,9 liters. Subsequent treatment occurs on potato seedlings 5-10 centimeters high at a dosage of 0,3-0,5 l/ha. This allows you to control annual dicotyledonous and cereal weeds, with the exception of tenacious bedstraw and black nightshade.
On varieties that are not resistant to metribuzin/prometrin, original preparations based on aclonifen make it possible to remove most of the spectrum of dicotyledonous weeds, with the exception of black nightshade. The specialist suggests solving the problem with nightshade using microencapsulated clomazone, which can be added to aclonifen and metribuzin as a partner drug. Microencapsulated clomazone helps control both black nightshade and bedstraw. The substance provides long-term protection against grass infestation, while perennial weeds, such as sow thistle and bindweed, are also inhibited. Important note: tank mixtures should only be used before potatoes emerge.
In situations where pre-emergence treatment has not been carried out on potatoes, it is possible to use aclonifen at a rate of 1-1,5 liters in pure form to control dicotyledonous weeds such as white pigweed, upturned acorn grass, knotweed and bedstraw. In this case, the height of the crop seedlings should be no more than 5-10 centimeters. Konstantin Onatsky emphasizes that aclonifen should not be mixed with graminicides and adjuvants.
In cases of severe infestation with perennial weeds such as thistle, rose thistle and bindweed, the specialist advises using MCPA-based preparations (10 g/l at a dosage of 15-500 l/ha) on 0,6-0,8 cm potato seedlings. We must not forget that such treatment is a serious stress for the crop, and its consequences must be mitigated with anti-stress products based on amino acids.
If potatoes are planted in a heavily weeded field using complex machines that immediately form a ridge, during pre-emergence treatment it is necessary to add preparations based on glyphosate or MCPA to herbicides based on clomazone, metribuzin or aclonifen. When the ridge is formed after a certain time, mechanical removal of weed sprouts does not occur. As a result, weeds appear much earlier.
Konstantin Onatsky also recalls the practice of using drugs based on prosulfocarb in addition to metribuzin or aclonifen. Prosulfocarb allows you to control mainly bedstraw and nightshade, as well as some grass weeds.
Nikolay Rozhnov calls the use of metribuzin-based drugs in weed control the “gold standard”. But he draws attention to a significant drawback of this active substance - slow decomposition in the soil, which is fraught with inhibition of a number of crops sown in the future. This can only be avoided by introducing restrictions on crop rotation, valid for up to 24 months. According to the expert, in the Bryansk region the problem is being solved with the help of the latest drugs based on prosulfocarb, which does not have such features.
To agrotechnical measures
Experts are unanimous in the opinion that weed control cannot be limited only to chemical methods.
Well-shaped combs are of great importance. Nikolay Rozhnov emphasizes that intensive soil movement during this process, repeated hilling of plants and cultivation with a harrow on sandy and sandy loam soils can achieve excellent results. On heavier soils, the effectiveness of mechanical control is usually insufficient.
According to Lyudmila Kostyagina, The reduction of weeds in the fields is facilitated by compliance with crop rotation, as well as timely vegetative cultivation combined with chemical treatment. She also includes planting green manure as an effective way to control weeds.
Irina Berg