Seed Treatment Application with Neonicotinoids

Protection of the environment is an important motivator for continuing to develop new products and methods for seed treatment. This innovative method has additional benefits which make it not only interesting for economic reasons but also from an ecological point of view. The advantages are self evident: the ai is only found where activity is desired.

Compared with broadcast spraying or in-furrow treatment with granules, seed treatment effectively reduces the treated area considerably, e.g. from a 10 000 m2 plot of arable land to around 60 m2 or 1 % of the corresponding field area (see Figure 4.5).

Moreover, seed treatment has less impact on non-target organisms and is not prone to drift, since the product is applied under controlled conditions (often in closed systems), which are not only independent of the weather, but also user safe, because the user does not come into direct contact with the ai during application.

In addition to seed dressing, film coating (for field crops and vegetables), pelleting (for sugar beets and fodder beets), pelleting and coating (sequential application of different film coatings) or multilayer coating (incorporation of insecticides and fungicides) also allow an effective, environmentally safe and ideal protection of young plants against insect attack and a variety of fungal diseases.

Applying the ai directly to the seed disinfects its halo surface. Soon after sowing, the plant absorbs the ai from the disinfectant halo through the roots

Furrow treatment with granule (approx. 500 m2

Whole area treatment (e.g. spray (10.000 m2))

Furrow treatment with granule (approx. 500 m2

Whole area treatment (e.g. spray (10.000 m2))

Figure 4.5 Compared to spray application, seed treatment reduces the overall treated area. While spray application of 1 hectare resulted in 10000 m2 of soil surface being in contact with active ingredient (e.g. neonicotinoids), an in-furrow treatment with granules covers only 500 m2. This is further decreased to less than 60 m2, i.e. less than 1 percent of one hectar, when choosing seed treatment technology. (Source: Bayer CropScience).

Figure 4.5 Compared to spray application, seed treatment reduces the overall treated area. While spray application of 1 hectare resulted in 10000 m2 of soil surface being in contact with active ingredient (e.g. neonicotinoids), an in-furrow treatment with granules covers only 500 m2. This is further decreased to less than 60 m2, i.e. less than 1 percent of one hectar, when choosing seed treatment technology. (Source: Bayer CropScience).

and forms a so-called protective zone of ai against insects or fungal pathogens in the soil around the seed grain. Finally, the growing plant transports the ai from the roots to the aerial parts of the plant and uniformly in its tissues of the upper leaves. In this way, the growing plant is protected ''from the inside out'' against pests and pathogens, which is also of benefit to consumers by making their food safer (see Figure 4.6).

Today, seed treatment is a standard technique used in many crops from highgrade seed, which involve intensive production methods, such as cotton, sugar beet, rice, wheat, barley, maize and market gardening. It offers farmers many advantages such as fewer spray applications, a reduction in agricultural machinery and maintenance cost, and considerable time saving, all of which help to increase income.

New opportunities for an innovative and sustainable agriculture have been opened up by the use of modern seed treatment application with the highly systemic neonicotinoid insecticides.90 The application amount (g ai ha-1) used per unit area is thereby reduced remarkably, as shown for neonicotinoids in corn (see Figure 4.7; spray > granules > seed treatment).91

Today, the three plant systemic neonicotinoids, imidacloprid (Gaucho), thiamethoxam (Cruiser) and clothianidin (Poncho), are widely used in various FS formulations (FS = flowable concentrate) for seed treatment applications in different crops, such as cotton, corn, cereals, sugar beet, oilseed rape etc. (see Table 4.4).

For example, as a corn seed treatment, clothianidin (Poncho) protects the young plants against early-season pests (soil and leaf pests), especially wireworms (Agriotes spp.) and hemipterans.92 In addition, chlothianidin is very

©A.i. is transported to the aerial parts of the plant and uniformly distributed in its tissues

Q The plant absorbs a.i. through the roots

Q A.i. is released from the seed immediately after sowing, quickly surrounding it

Q The plant absorbs a.i. through the roots

Q A.i. is released from the seed immediately after sowing, quickly surrounding it

Updake Insecticide Treated Seeds

Figure 4.6 Formation of a protected zone in: (1) the soil, (2) root uptake and (3) systemic translocation, after seed treatment. Active ingredient (a neoni-cotinoid) can be applied in combination with further active substance classes (e.g. fungicides, other insecticides) in one product in order to create synergies. (Source: Bayer CropScience).

Figure 4.6 Formation of a protected zone in: (1) the soil, (2) root uptake and (3) systemic translocation, after seed treatment. Active ingredient (a neoni-cotinoid) can be applied in combination with further active substance classes (e.g. fungicides, other insecticides) in one product in order to create synergies. (Source: Bayer CropScience).

effective against different species of Diabrotica (corn rootworm), such as the western (Diabrotica virgifera virgifera), northern (D. barberi), southern (D. undecimpunctata) and Mexican (D. virgifera zeae) corn root worm.

Generally, larvae feed on primary and secondary corn roots. Excessive loss of root tissues from larval feeding can cause instability of the corn plants which results in lodging. Massive lodging reduces the harvest efficiency and, therefore, severe losses in yields. Feeding damage on roots will also reduce water and nutrient uptake, root and plant growth, and ultimately yield, especially under favorable dry soil conditions.92

The physico-chemical properties of clothianidin are theoretically very close to ideal, e.g. water solubility (0.327 g l 1) and lipophilicity (logPow = 0.7) (see section 4.3.3; Table 4.2) and are in a moderate range which allow a uniform distribution within the rooting zone of corn establishing a halo around the rhizosphere. In addition, the microbial degradation of clothianidin also remains on a moderate level. Therefore, the ai is continuously available to the plant over an extended period of time at the required dosage. The presence of clothianidin, even in the youngest roots far away from the initial point of application (kernel), was demonstrated in autoradiograms of roots of six-week-old corn plants treated with 14C-labelled clothianidin (see Figure 4.8).

As described earlier, uptake of the ai by insect pests takes place primarily through oral ingestion, and therefore feeding of sufficient amounts of root g a.i./ha

Lindane Carbo- Fipronil IMI CLOTHI furan

Spray

Granules

Seed treatment

Figure 4.7 Improvements in application methods for crop protection products in maize due to the introduction of neonicotinoids. g a.i./ha (applied grams active ingredient per hectare in maize), IMI (imidacloprid) and CLOTHI (clothianidin). (Source: Bayer CropScience).

Table 4.4 Neonicotinoid insecticides used in seed treatment applications.

Neonicotinoid Brand Main insecticides names formulations* Crops (selected examples)

Imidacloprid Gaucho FS 480

FS 600

Thiamethoxam Cruiser FS 350 Clothianidin Poncho FS 600

Canola, cereals, corn, cotton, oil seed Rape, pastures, potatoes, rice, sorghum, sugar beet, sun flowers Cotton, sun flowers, soybeans, maize, sorghum, sweet corn, rice, sugar beet, oil seed rape, cereals, wheat, potatoes Canola, cereals, corn, sunflowers, sugar beet

*FS (Flowable concentrate for seed treatment).

(0.1 to 0.3 mgg 1 root mass) or leaf tissue containing clothianidin is essential for

pest intoxication.

In addition, synergistic combinations of both imidacloprid (Gaucho) and clothianidin (Poncho) with members of different insecticide classes, such as pyrethroids (e.g. Imprimo, Chinook, Poncho Beta) or oxime carbamates like thiodicarb (e.g. Aeris, CropStar), have also been developed (see Table 4.5).

Bunt, smut (genus Tilletia) and fusarium fungi (e.g. Fusarium moniliforme, F. proliferatum in maize) are just a few of the most dangerous diseases of cereal

Figure 4.8 Clothianidin ensures long term control of below- and above-ground corn pests. The autoradiograms with 14C-labelled clothianidin equivalents were prepared six weeks after sowing and demonstrate that even the youngest roots far distant from the kernel contain equivalents of the active ingredient. (Source: Bayer CropScience).

Figure 4.8 Clothianidin ensures long term control of below- and above-ground corn pests. The autoradiograms with 14C-labelled clothianidin equivalents were prepared six weeks after sowing and demonstrate that even the youngest roots far distant from the kernel contain equivalents of the active ingredient. (Source: Bayer CropScience).

Table 4.5 Combination for seed treatments of neonicotinoids with insecticides and fungicides.

Neonicotinoid insecticide

Brand names

Combination partners (insecticide, fungicideb) in FS formulation*

Imidacloprid

Thiamethoxam

Clothianidin

Aeris; CropStar Imprimo; Montur Chinook

Monceren G; Prestige Cruiser Extreme 250 Cruiser OSR Helix

Poncho Beta Prosper

Thiodicarba Tefluthrina beta-Cyfluthrina Pencycuronb

Azoxystrobin,b fludioxonil,b metalaxyl M,b

Metalaxyl M,b fludioxonil,b

Fludioxonil,b difenoconazole,b metalaxyl Mb beta-Cyfluthrina

Thiram,b carboxin,b metalaxylb

*FS = Flowable concentrate for seed treatment.

grains, causing yield losses of up to 60 percent. Typhula root pathogens (Typhula incarnate Lasch, T. ishikariensis Imai) live in the soil and are a serious threat to crops such as winter barley. Powdery mildew (e.g. Uncinula necator) is a windborn pathogen which threatens barley and wheat. The three neonicotinoid combination seed treatments have therefore been developed to include up to three different fungicides (four-way mixture = 4 components) as outlined in Table 4.5.

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