Fighting for daily bread - pagS at the service of agriculture

Approximately 12 % of the world crops are lost because of plant diseases. The estimates of losses caused by phytopathogens in agriculture and forestry are as high as milliards of dollars.

Almost one third of the crops are lost in Russia during raising, storing, and processing of agricultural produce. Experts consider plant contamination with various pathogenic microorganisms and saprophytes one of the main reasons for such a high percentage of losses.

Application of biocidal chemicals for treatment of seeds protects the plants from diseases and increases the crop yield.

Test results have shown that PAGs can ensure reliable protection of plants and help to increase the yield of fruits, vegetables, and cereals.

Pathogenic microorganisms (bacteria, viruses, and fungi) are probably the greatest enemies of agriculture. They live in soil; wind, birds, and insects are their vehicles. Coming in contact with plants, fungi spores and pathogenic microbes contaminate cereals and fruits, and, via forage crops, they infect cattle. Infection often reaches humans via food chain.

People tried to fight such organisms using agrochemistry for many decades. However, unlimited application of chemicals in agriculture, which was matter of fact in the time past, has already played an evil joke with the ecosystem as a whole, and with man himself. Nowadays new efficient chemicals are required that should be effective against pathogens, while remaining environment-friendly.

Agricultural monsters

The most urgent problem of plant cultivation is ensuring sound state of soil. The fecundity of soil depends greatly on the microorganisms inhabiting it (bacteria, fungi, etc.).

If the soil contains many phytopathogens (pathogenic microorganisms causing plant diseases), the plants grow slowly, are often damaged by weeds and insects, and become weak and ill. Unfortunately, the area of such “unhealthy” plough-land is ever increasing, even in countries where the level of agrotechnology is relatively high. In Japan, e.g., almost 90 % of plough-land are thus exhausted.

If no measures are taken to fight the phytopathogens, they can lead to 20-50 % decrease of cereal yield or even completely destroy the harvest thus causing great losses to the economy. However, this is not the only hazard of phytopathogens.

Mycotoxins produced by these pathogens and accumulating in fruits and grain are very dangerous for human health. Forty-seven of the fungi known up to date are highly toxic, 15 of them have cancerogenic properties. Mycotoxins damage genes, derange immunity, and cause oncological diseases. Fungi of genuses Aspergillus, Alternaria, Fusarium, Penicillium, Mucor, Rhizopus are most often the sources of toxins.

Fusarium contaminates soils and causes root rot of many plant types, forest ones as well as agricultural. Fruit trees infected with Fusarium toxins wither and loose foliage. Fungi of Fusarium species when settling on cereals, contaminate them with ãîìèòîêñèí vomitoxin(???) that makes grain unsuitable for consumption by humans and animals.

Ubiquitous application of chemicals

Simple measures of soil disinfection (steaming, sprinkling with weak disinfecting solutions, e.g. sodium permanganate solution) are often insufficient to destroy microbes and fungi.

Certainly, various pesticides can be actively used to fight phytopathogens. However, this way is not the best one by far. Nowadays a wide group of toxic substances named fungicides are used to fight phytopathogens. Though the currently used fungicides produce a positive effect, they make the treated grain toxic and pollute the environment. This aggravates the already bad state of environment.

Besides, phytopathogens develop immunity to the pesticides. This, in turn, calls for the increase of pesticide dosage.

Consider, e.g., the chemical pesticides widely applied in agriculture. They have a wide range of activity, but they also have a number of drawbacks. The wide range of activity itself can be a drawback, because pesticides often produce the non-specified effect: causing death of so called “non-target” organisms such as useful insects or parasites of harmful ones. Besides, chemical pesticides are often toxic for humans and animals.

Often the organisms, which are the aim of chemical pesticides, develop immunity to their action. This leads to the necessity either to perform repeated treatment or increase the concentration of these compounds. Despite the almost instant action, chemical pesticides can cause new problems for human health and increase the environmental pollution.

The deficiencies of the currently used chemicals (of their chemical, physical, and mechanical properties) lead to a number of environmental problems: pollution of soils, surface and subterranean waters, the agricultural produce itself, etc.

For example, increased dosage of nitrogen fertilisers leads to the increase of concentration of nitrates in the agricultural produce. Application of phosphor fertilisers results in soil contamination with many toxic chemical elements as fluoride, strontium, etc.

Natural phosphates contain such radioactive elements as uranium and radium. Phosphor forms compounds with such elements as calcium, aluminium, and iron and therefore most of it remains in the soil, and further it often gets into water basins. This leads, among other, to water pollution and rapid propagation of algae.

Potassium fertilisers can also have a negative effect on the environment because they contain the so-called ballast chemical elements such as chlorine and sodium. The latter, accumulating in the soil due to systematic application of increased fertiliser doses, decrease the soil fecundity. These elements also get into subsoil water increasing its salt content.

The excessive amount of chlorine, sodium, and potassium results in accumulation of these elements in the agricultural produce and forage that, in turn, can have a negative effect on the health of the cattle. The metals contained in the potassium fertilisers (cadmium, mercury, lead, and aluminium) can accumulate in live organisms, infiltrate the subterranean waters, etc.

Apart from the obvious environment-unfriendliness, application of pesticides has yet another essential drawback. Further application of chemicals to soils already saturated with pesticides and artificial fertilisers, together with the use of heavy agricultural machines, can aggravate soil erosion and, at last, make the arable land a waste.

Thus the issue of developing agriculture in harmony with the environment (or at least minimising the negative environmental impact) becomes very urgent.

The environment-friendly polymeric biocides polyalkylene guanidines (PAGs) developed and produced by the Institute of Ecotechnologies can be a great help in this situation. These biocides have a high antimicrobial and antifungal activity.

Disinfection of soil contaminated with pathogenic microorganisms (especially Fusarium spp. fungi) using PAGs has a positive effect on the soil fecundity. Combining PAGs with other substances can also protect soil from wind and water erosion.

PAG biocides are environment-friendly. They are well soluble in water, have neither odour nor smell. PAGs form no toxic compounds, either through reaction with organic substances, or via decomposition. This ensures their safety both for the personnel working with these chemicals, and for the environment.

As you have sown

Disinfection of soil alone, for all its efficiency, can not guarantee the growing of strong and healthy plants. The matter is that the seed materials (grain, bulbs, etc.) can also be infected with pathogenic microorganisms.

Microorganisms are classified into saprophytes and phytopathogens according to their action on the seeds. Saprophytes feed on the nutritive substances contained in the seeds. However, the protective functions of the seeds themselves prevent propagation of such microorganisms. Phytopathogens can cause plant diseases of microbiological origin: bacterioses, mycoses, and virus diseases.

Fusariosis, seed rot, root rot, septoriosis, snow mould, etc. are the most widespread diseases of seed materials. The infected seeds put forth weak and unhealthy growth, and often no growth at all, therefore the traditional way to fight pathogenic microorganisms is to treat the seeds with pesticides before sowing.

Biocides produced by the Institute of Ecotechnologies can also find a wide application in this technology. A number of tests have been performed in various regions of the Commonwealth of Independent States. The results of these tests have shown that using PAGs for treatment of seeds protects the plants from diseases and helps to increase the productivity of crops.

For example, the experts of the All-Russian Research Institute for Chemicals for Plant Protection have shown that treatment of flaxseeds (sort A-93) can successfully fight such diseases as bacteriosis and êðàï÷àòîñòü. Application of PAGs resulted in germination energy and germination capacity (ýíåðãèÿ ïðîðàñòàíèÿ è âñõîæåñòü) of the seeds increasing by 10-20 % and 4-5 %, respectively.

The tests performed at the All-Russian Research Institute for the Studies of Flax Cultivation (Torzhok, Tver Region) have shown that the treatment of flax seeds with a water solution of this bactericidal polymer increased the productivity of crops by 12 %.

Pridnestrovskii Agricultural Research Institute (Tiraspol, Moldova) tested the efficiency of PAGs on the seeds of peas and tomatoes. Treatment of the vegetable peas of the sort “Yuzhnyi” suppressed the pathogenic microorganisms by 58-79 %. This was accompanied by the increase of productivity by 1.3-2.4 metric tons per hectare.

Treatment of tomato seeds of the sort “Onyx” infected with black patch disease of bacterial origin allowed increasing the tomato yield by 5-19 metric tons per hectare.

Growth protection

Pathogens causing infectious diseases often attack the plants during the vegetation period. Harmful microorganisms can cause a variety of diseases: scab, anthracnose, melanosis, Phytophthora disease, septoriosis, cancer, and bacterial necrose… Citrus are prone to stubborn disease (Spiroplasma citri Saglio); bananas can be infected with anthracnose, pyriculariosis, bacterial mould, and fungal diseases; mango’s infestants are mildew (Oidium) and scabs. Often the plants often suffer with a number of various infection diseases at the same time.

The traditional way to fight pathogenic microorganisms infecting plants is application of agriculture-specific chemicals for various purposes, including hothouse disinfection. However, wide application of toxic chemicals pollutes the environment and results in adaptation of microorganisms to the chemicals.

Biocides developed and produced by the Institute of Ecotechnologies are very effective for treatment of plants against diseases caused by Septoria, Fusarium, Phytophthora, Alternaria, Rhizoctonia, Helminthospora, and other species.

Test results have shown that PAGs can reliably protect plants. This leads to the productivity increase of cereal, fruit, and vegetable crops. The efficiency of PAGs is sometimes 10 times greater than that of biocides produced outside Russia.

Thus, e.g., the All-Russian Research Institute for plant protection chemicals performed tests in the central regions of the European part of Russia. The tests have shown that PAGs can effectively (80-82 %) fight potato phytophtorosis and increase the potato productivity by 6.2-6.3 metric tons per hectare. Application of PAGs with dosage 1.2 kg per hectare allowed increasing the cucumber yield by 4 metric tons per hectare.

Tests performed at the Pridnestrovskyi Agricultural Research Institute (Tiraspol, Moldova) have shown that PAGs suppress propagation of Peronospora fungi in onions by a factor of 3-5. The productivity increased by 107-110 kg per hectare due to the application of PAGs. Biocides were proven to be effective against bacteria that cause brown bacteriosis of beans of the “Predgornaya” sort.

Bactericidal activity of PAGs was as high as 96 %. Application of the PAG biocides allows increasing the yield of beans by 370-500 kg per hectare. The number of tomatoes of the sort “Onyx” infected by the bacterial plant cancer decreased by a factor of 20.

HOW TO PRESERVE THE CROPS

Growing crops and gathering harvest is still not the whole agricultural cycle. The produce should be preserved and shipped to the customers. However, a large part of the crops is lost during storage and transport.

Saprogenic bacteria and spores of fungi are always present in numbers in the air and on the surface of the agricultural products. Damaged, unhealthy, or simply over-ripe fruits are prone to be infected with pathogens.

Fruits and vegetables are mostly infected by various types of rot caused by fungi of the Penicillium, Sclerotinia, Alternaria, Fusarium, Rhizopus, Aspergillus, and other genuses. Propagation of saprogenic microorganisms on vegetables during storage leads to essential (over 50 %) losses of the produce.

The main enemies of the forage are the enteropathogenic Coli bacteria, salmonellas, and bacteria of the protea group, as well as anaerobic microorganisms and various fungi.

Treatment of the crops with biocides before putting them into the storage allows reducing the losses essentially. The experiments have shown that, e.g., PAGs completely suppress the following diseases of potatoes during winter storage: black stem, wet rot, rubber rot, fusariosis, macrosporiosis, phomosis, collar rot, common scab and silver scurf, and rhizoctoniosis.

Treatment of wet grain with PAGs ensures its safe storage and also enhances the quality of flour and the baked bread.

Stock Company “Agronom” in Krasnodar Region of Russia tested the PAGs on apples. The tests have shown that the apples of the varieties Corey, Red Delicious, Ida Red, and Semerenko Rennet treated with PAG biocides and then stored for two months in refrigerator showed almost no traces of decay.

The tests performed at the test farm “Tsentralnoe” (Krasnodar) have shown that the percentage of apples decayed during 4-month storage in a refrigerator decreased by 36-91 % due to the treatment with PAGs.

The damage caused by the pathogenic microorganisms is not limited to the decay of agricultural produce. The metabolism process of the microbes releases dangerous toxins, spores, and putrefaction products.

These, in turn, aggravate the damage of the agricultural produce and endanger the health of people working at the storage facilities. The experts of the Institute of Ecotechnologies recommend biocidal paints of the Biokrapag series and the Septopag varnish for disinfection of storage facilities for agricultural products. These paints can be a good complement to the water solutions of PAGs.

Konstantin Efimov,

Director of the Institute

of Ecotechnologies