Among our cultivated crops, the sunflower is perhaps the one with the widest range of genetic variations.Among others, downy mildew resistant, downy mildew resistant, high, low oleic acid content and different types of herbicide tolerant lines that have already been grown in at least three crops.Producers are required/possible to choose from these combinations.The sunflower has become one of the most important cultural crops in Hungary, and its production area has exceeded 600,000 hectares for years.
The sowing of sunflower is due in the first or second decade of April, so its weeds are mainly made up of the heat-loving T4 and G1, G3 species.The typical dicotyledonous annual species of its weed group are sedges, gooseberries, bitter grasses, snapping sedges, silk mallow, in some places, sedges and crow's feet.A typical pest of dicotyledonous perennials is the field acacia, the small weevils and the hedge weevils.From the group of monocotyledons, the sorghum, the fly ash species and the millet genus, the perennial buckwheat and the pine sorghum are the most common 41. Tribenuron Methyl 97% Tc
Based on the work of Pinke-Karácsony (2010), the species of the nesting family occupy the most space in sunflowers, primarily through the wormwood, the Serbian thorn species, and the field acat.Today's prominent problem is caused by ragweed, which, in addition to direct crop damage, also raises significant human health problems, its occupation of space entails official measures (e.g.: Decree 43/2010 (IV. 23.) FVM decree; 221/2008. (VIII. 30 .) Government Decree).6, 15, 36
A special, parasitic weed of the sunflower is the sunflower butterflower or sádor species.In Hungary, they are found in the eastern and southeastern parts of the country, and they are primarily a plant protection problem in the Mediterranean regions of Europe (e.g. Bulgaria, Turkey).13, 48
Until the mid-2000s, the selection of sunflower areas was largely determined by the area's weed flora, as protection against some weed species was limited.In the past, the cornerstone of sunflower weed control was the protection against large-seeded dicotyledonous and perennial dicotyledonous species that are difficult to eradicate with soil herbicides (e.g. snapdragon, field acat, etc.), as well as species closely related to it (wort-leaved ragwort, milk thistle species).Most of the herbicides that could be used were herbicides that can be applied pre-emergently, the effectiveness of which is limited and strongly depends on weather factors.In order to have the effect, you need the right amount of wash-in precipitation.42, 10
The possibility of post-emergence weed control against dicotyledons in sunflower was low compared to other crops.Only flumioxazin could be used post-emergently.The herbicide does not provide adequate results against, among others, white gooseberry and ragweed, and it causes scorching symptoms on the cultivated plant.56, 11, 23
In addition, several previously essential herbicides used against pre-emergent dicotyledons have now been withdrawn, primarily e.g.oxyfluorfen and linuron.
Chemical weed control of sunflower can be carried out with preplant, prepost, presowing, preemergence and postemergence application methods.
In the case of Preplant or Prepost application, glyphosate with total effect is used before or after sowing sunflowers, but before emergence, which is important in the presence of perennial weeds.Based on our own experiments, good results can be achieved with the technology against field acat.Prepost application proved to be more virtuous than preplant.20, 21
The essence of the presowing technology is to spread the herbicide(s) shallowly into the soil before sowing.In dry springs and loose soils, a good effect can be achieved by using the technology.As a result of the application, the chemical can exert its effect regardless of the wash-in precipitation.Fluorochloridon and benfluralin active substances can be used in addition to the presowing method of application.62, 63
Terbuthylazine, fluorochloridone, metobromuron, flumioxazin are the active ingredients that can be used against dicotyledonous weeds with pre-emergent application in sunflower.Acetamide derivatives such as s-metolachlor, dimethenamid, petoxamide, pendmethalin can be used against monocotyledons, but prosulfocarb and benfluralin are also licensed.In order to achieve the widest possible weed-killing effect, the pre-emergent monocotyledonous and dicotyledonous herbicides are used in factory or tank combinations.7, 12, 27, 34, 56 A widely used factory combination is s-metolachlor and terbuthylazine (Gardoprim Gold), dimethenamid-p and pendimethalin (Wing P), and a common tank combination of fluoride chloride and s-metolachlor (DuRacer) .
The PROTOX-inhibiting herbicide flumioxazin (and oxyfluorfen in its old age) gives good results when the weather conditions are suitable, e.g.against the porcupine species, the white gooseberry, and the leafy bitterwort.Their effect is not comprehensive against wormwood, silk mallow, and burdock thistle.11, 34
A high dose of fluorine chloride should be used in sunflowers, which can be used to suppress, among others, the white goosefoot, the hairy pig bream 11, orin areas moderately infected with fallow grass, we can achieve adequate results with it.3, 4
The effectiveness of pre-emergent preparations requires the appropriate amount of wash-in precipitation.Depending on the water solubility of the products, the amount is 10–20 mm within 2 weeks after application.
Herbicide-tolerant sunflower weed control technologies are based on resistance to ALS (or AHAS) enzyme-inhibiting herbicides.When the agents are used, the synthesis of the amino acids valine, leucine and isoleucine stops in plants due to the blocking of one of the key enzymes, hydroxyacetic acid synthase (AHAS).41, 48
Several SU- and IMI-tolerant cultivars have already been created by combining biotechnological methods and traditional breeding.Plant varieties of this type do not contain genes from foreign organisms, so they belong to non-transgenic herbicide-resistant plants.Among them, the technology based on imidazolinone resistance (also known as: Clerafield) can be said to be the most successful.This is based on the fact that imidazolinones control monocotyledons and dicotyledons well, but are only ineffective against butterfly plants 53, whose importance in field weed flora is subordinate 33. The use of imidazolinones was also facilitated by the development of imazamox, which is slightly persistent and can therefore be used without harmful after-effects.1
The first imidazolinone-resistant crop sunflower lines were produced in Kansas using pollen from wild sunflowers that had become resistant.Versions of this type are designated as IMISUN (or: Clearfield).Herbicide resistance was caused by the alanine (205)-valine substitution (Arabidopsis thaliana position).In IMISUN sunflowers, tolerance is provided by a main gene (Imr1) and a secondary gene (Imr2) with extrachromosomal inheritance (also called: modifying factor or e-factor).This results in moderately high resistance to imidazolinones and partial resistance to sulfonylureas.2, 26
The second source of imidazolinone resistance was developed under laboratory conditions, using the active ingredient imazethapyr, which was named "CLHA-PLUS" (or Clearfield Plus).In CLHA-PLUS variants, tolerance is due to the alanine-threonine amino acid exchange at codon 122 of the amino acid chain (Arabidopsis thaliana position), which provides specific imidazolinone resistance (thus SU sensitivity).CLHA-Plus lines provide a higher degree of resistance to imidazolinones.The absence of a modifying factor simplifies the breeding process.45, 46
The tribenuron-methyl-tolerant lines were produced under laboratory conditions, similar to Clearfield Plus sunflower.The tolerance resulted from the proline-leucine (197) (Arabidopsis thaliana position) substitution 16, the hybrids tolerate the 22 g/ha dose of tribenuron-methyl without damage.9
Sala-Bulos (2011).A new mutation was found in wild sunflower populations in Argentina, which results in a high degree of resistance to imidazolinones and sulfonylureas.The biotypes were named RW-B.Through genetic studies, it was shown that the resistance is a consequence of the tryptophan-leucine amino acid exchange occurring at position 574 (Arabidopsis thaliana position), and it is suggested that they can be used to develop new HT sunflower lines.
In summary, 4 mutations have been identified in sunflower so far, which provide different types of resistance to imidazolinones and/or sulfonylureas.They form the genetic basis of cultivated herbicide-tolerant sunflower hybrids/varieties.
Clearfield sunflowers were introduced to the market in Turkey (Sanay hybrid) and the USA in 2003, and today this plant protection technology is used in many countries (since 2005 in Hungary, the first hybrid is Rimisol 25).Many IMI-tolerant hybrids can currently be grown in Hungary, some of which belong to the IMISUN line (Clearfield, designation: CL) and others to the CLHA-Plus (Clearfield Plus, designation: CLP) line.
Preparations containing imazamox can be used for weed control of Clearfield sunflower in Hungary, which gives outstanding effectiveness against the species of snapping mask, hellebore, hogweed, black tip, cruciferous, and rapeseed.In addition, it destroys well the species of white gooseberry, wormwood, burdock thorn, ivy, as well as the monocotyledonous sedge, wild millet and fly ash species.22, 23, 30, 32, 43, 47, 37, 54. specimens are partially regenerated.23
When Pulsar 40 SL is used in dry weather, a decrease in efficiency may occur in the case of the waxy-leaved white swan.18 Pulsar 40 SL results in medium or weak efficiency against field acat.51, 58 The effectiveness of weed control can be significantly increased with the use of prepost technology when there is a high coverage of field acat.21
When imazamox is used, temporary yellowing and growth depression may occur in sunflowers.However, these symptoms do not harm the sunflower.24, 40
By using CLHA-Plus type imidazolinone-tolerant sunflower lines, it was possible to develop new formulations of imazamox and/or to increase the herbicidal effect of imazamox by adding an adjuvant.
The herbicide Pulsar Plus was introduced in Hungary in 2016, which contains a complex adjuvant system as a factory combination in addition to the active ingredient content of 25 g/l imazamox.Based on the results of Szántó (2020), Pulsar Plus resulted in better efficiency against ragweed, white gooseberry, and green fly ash than Pulsar 40 SL in all cases.Neshev et al.(2020) found that the white gooseberry and the silky mallow can be successfully controlled using Pulsar Plus.Pulsar Plus also proved to be more effective than Pulsar against the spray.40 SL, 29, 38
The reason for the increase in efficiency is the amount of imazamox that enters the leaf tissue of the weeds faster and in larger quantities.As a result, the effectiveness against those weeds against which the Pulsar 40 SL was not fully effective was improved.These include those with waxy leaves, such as white gooseberry or narrow-leaved;those with hairy leaves, such as wild millet or silk mallow;and they are prone to lateral branching already at the age of 6–8 leaves, like ragwort.35
However, it is important to know that only Pulsar 40 SL and other approved imazamox-containing herbicides can be used to weed Clearfield sunflowers, because Pulsar Plus (and several of its analogues) can damage them.Clearfield Plus sunflowers must always be weeded with the more effective Pulsar Plus and its analogues herbicide.Traditional imazamox-containing products do not have a license for use here.Pulsar Plus herbicide can only be used in Clearfield Plus (CLP) sunflower hybrids.In addition, Pulsar Plus and its analogues are not licensed for weed control of legumes (e.g. soybeans, peas).In summary, Table 1.
The active substance tribenuron-methyl is basically used for SU sunflower weed control, which has well-known dicotyledonous properties from the weed control of cereals, and its use is usually recommended with the addition of 0.1% Trend.According to its spectrum of effects, it can be particularly well used against the snapping mask, the porcupines, the hellebore, the white goose, the black-bill, the crucifers, and the rapeseeds.It has a good effect on burdock and against spawning.It is effective, but not fully effective, against bitter gorse and black-leaved ragwort 5, 17, 19, 54, 55, 58. In our experiments, tribenuron-methyl was less effective than imazamox in our tests against ragwort. 23. Against field acat however, it has a better weed-killing ability than imazamox 54, 58. From 2019, herbicides containing tribenuron-methyl + thifensulfuron-methyl active ingredients can be used for SU sunflower weed control.64
Tribenuron-methyl has only divalent killing properties.Monocotyledons can be effectively controlled with pre-emergence or post-emergence graminicide treatment.
Halauxifen-methyl (arylex) belongs to the group of synthetic auxins and within it to the new aryl-picolinate subgroup.It was developed for the weed control of cereals against dicotyledonous weeds 29. In the USA, at a dose of 5 g ai/ha, its successful use against glyphosate-resistant invasive grass and wormwood has already been reported 59, 60, 61. In Hungary, it can be used post-emergently in sunflowers at a dose of 3 g ai/ha.Kerekes et al.(2019) reported the outstanding effectiveness of halauxifen-methyl against wormwood and silk mallow.Nagy (2020) also observed outstanding effectiveness against the worm-leaved ragweed, a good effect against the white gooseberry and pokolvar gooseberry, and a weak effect against the hairy pig sedge 60 and the snapping mask.The use of the active ingredient is permitted from the stage of 6 true leaves of the sunflower and can also be used against more advanced weeds, although the treatment should not be postponed until the end in order to avoid yield reduction caused by weeds.
With the spread of herbicide-tolerant sunflowers, we ourselves cultivate ALS-resistant weeds in our areas.When setting up the sowing structure, it is worth paying attention to the type of sunflower resistance, which can largely determine the success of the weed control of the subsequent crop.Based on our own experiments, Express sunflowers typically have a wide range of resistance to SU preparations and also tolerate imazamox well.Clearfield sunflower orphans have heritable resistance to imazamox and partial resistance to several SU agents.On the other hand, the Clerafield Plus hybrids are only resistant to imazamox and show high sensitivity to SU preparations.This is important primarily because of the soybean weed control technology, in which good efficiency can be achieved against CLHA-PLUS hybrids using thifensulfuron-methyl.18, 19
Undoubtedly, the introduction of herbicide-tolerant sunflower technologies revolutionized the technology of sunflower weed control, with the use of which sunflower cultivation became safe, and it became possible to bring more areas under sunflower cultivation.In the Central and Eastern European region, HT technologies are used in a significant part of the sunflower areas, which are affected by ragweed infestation, the rise of invasive weeds (e.g. burdock thistle), butterwort Orobanche spp.due to its spread, it has a prominent role.in Bulgaria, e.g.In 10–15 years, the application rate of HT technologies is 85–90% 54;In Hungary, in 2019, HT sunflowers were located on 96% of the production area, of which Clearfield hybrids were grown on 68% 52.
In order to carry out successful sunflower weed control, it is necessary to apply an approach according to the principles of integrated weed control, according to which all means of plant cultivation are used to carry out weed control.Among other things, knowledge of weed flora, crop rotation, tillage, increasing the competitiveness of cultivated plants, herbicide rotation, biological control methods, application of mechanical control, etc.in order to minimize economic, health and environmental risks 50.
In addition to all this, the selection of genetic bases is of particular importance in the case of sunflower.The combined application of the technologies available for weeding sunflower and the chemicals that can be used requires expertise, as weeding planning must already be taken into account when choosing the seed.The seed and the applied post-emergence herbicide are inseparable partners during the growing season.
Both imazamox and tribenuron-methyl are effective preparations, but it is not worth basing the chemical weed control of sunflower exclusively on post-emergence agents.On the one hand, if the target pests only come into contact with ALS inhibitors, it can easily lead to the selection of resistant weed biotypes.On the other hand, with successful pre-emergence treatments - even if they do not provide a complete weed-killing effect - during the initial development of the sunflower, a good weed-killing effect can be ensured, thus intensive initial crop development 24.
Accordingly, the majority of manufacturers recommend post-emergence herbicides in combination with pre-emergence herbicides.
Summing up the post-emergence effects, it can be said that the effect of imazamox is stronger against the fallow grass and sunflower weevil than that of tribenuron-methyl.The latter active ingredient, on the other hand, has a better effect against field agate than imazamox.Against other important dicotyledonous weed species, the two technologies result in almost the same effect.Imazamox has a herbicidal effect against monocotyledons.
The outstanding feature of the active ingredient halauxifen-methyl is that it can be used regardless of the hybrid type.Its importance can be outstanding primarily in the control of ragweed, however, its effectiveness does not extend to monocotyledonous weeds and it has only a partial effect against several of the dicotyledonous weeds, which are important in sunflowers.
Among the HT lines, the advantage of using CLHA-Plus (Clearfield Plus) sunflowers should not only be stated in the enhancement of the weed-killing effect, but at least as important as its specific imidazolinone tolerance, which significantly facilitates the management of weed killer auctions.
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