Pelleted Seeds Research Articles

The fate of some carbamate insecticides after low-dose application techniques

The application rate of soil insecticides can be reduced using new techniques that allow a better positioning of the pesticide, i.e. close to the seed or seedling to be protected. In the sugar beet crop, for example, this can be achieved using seed treatment or spot application techniques. A better knowledge on the fate of pesticides that are applied using these techniques may help in avoiding some failures due to a lack of efficacy of the treatment or a lack of selectivity towards the plant material (phytotoxicity). Two examples are shown where carbamate insecticides are used at reduced application rate. In the first, carbofuran or carbofuran generating insecticides are applied to pelleted seeds at low dose. The studies have shown that with some particular combination of active ingredients and coating conditions it was possible to have a continuous release of small amounts of carbofuran in the soil that can give a good protection with limited risks for phytotoxicity. In the second example, the distribution of aldicarb in the soil and its uptake by the seedlings have been studied after full-dose application in the sowing furrow or after half-dose spot application near the seeds. It appeared that an important amount of the pesticide remains in the soil and is not taken up by the plant when the full-dose application technique is used. These results are in good agreement with that obtained in the field trials since it appears that the control of the aphid population on the sugar beet leaves is very satisfactory using the spot application (half-dose) technique.

The effect of seed treatment and seed covering medium on the establishment of crisp lettuce

SUMMARYThree experiments examined the effects on seedling emergence and seedling weight of covering pelleted, natural and pre-germinated seeds of the variety Pennlake with soil and other media.Covering seeds with a peat-vermiculite mix gave significantly greater, earlier and more uniform emergence and seedlings with a lower coefficient of variation (c.v.) of weight than covering with soil.Seedlings from pre-germinated seeds emerged more rapidly than those from natural and pelleted seeds and tended to be heavier when harvested 24 or 41 days after emergence. However, natural seeds consistently gave more uniform emergence than the other seed treatments and the lowest c.v. of seedling weight.

Comparisons of the use of pre-germinated, dry and pelleted seeds for block-raising of glasshouse lettuce

The use of pre-germinated seeds for establishing glasshouse lettuce in peat blocks was compared with dry and pelleted seeds. Sowing pre-germinated seeds gave between 1 and 6% higher seedling emergence than from pelleted seeds and between 1 and 3% higher emergence than from dry seeds. Seedling emergence was reduced from 100% to 56% when the seeds were covered with 5 mm of silver sand compared with no cover. Seedling emergence from seeds covered with Agrigel (sodium alginate) was reduced by 24% at a concentration of 0.25% and by 62% at 0.7% compared with no cover. Guar (a natural gum) and Laponite (a synthetic clay) gels also reduced emergence on certain occasions but not by as much as Agrigel. Satisfactory levels of emergence were obtained when seeds were sown into blocks having an inverted, cone-shaped depression for locating the seeds, but the seedlings showed poor root-hair development and had elongated hypocotyls. Normal seedling growth and high levels of emergence were obtained from the seeds sown into blocks having cylindrical holes 10 mm in depth and 5 or 10 mm in diameter. Pre-germinated seeds invariably emerged earlier than pelleted or dry seeds. At low propagating-temperatures (12.0°C maximum and 5.0°C minimum), emergence was 4 days earlier from pre-germinated than from dry or pelleted seeds and 2–3 days earlier at high temperatures (21.0°C maximum and 9.0°C minimum). Coefficients of variation of seedling weight at planting were lower from sowing pre-germinated than pelleted or dry seeds, but these differences were not evident at harvest.

The effect of sowing pre‐germinated seeds of lettuce (Lactuca sativa) on seedling emergence

SUMMARYGlasshouse and field experiments were conducted to investigate the effects of sowing both untreated and pre‐germinated seeds, with or without a gel carrier, and also pelleted seeds into soils of different moisture contents and at different temperatures on seedling emergence of lettuce cvs Cobham Green and Avondefiance.Pre‐germinated seeds with radicles 1–2 mm long gave, on average, 15 and 4% higher final percentage emergence than untreated and pelleted seeds respectively. Sowing pre‐germinated seeds having radicles longer than 2 mm gave more variable levels of emergence and often reduced emergence, particularly when they were sown into dry or drying seedbeds. Increasing the rate of gel carrier from 0 to 30 ml m_1 of row reduced emergence progressively from 67 to 30%. Pre‐germinated seeds emerged 2–5 and 3‐0 days earlier than untreated and pelleted seeds, respectively, at a soil temperature of 10 oC; at 15 oC the corresponding figures were 0–5 and 3–5 days. Sowing pre‐germinated seeds reduced the spread (i.e. variability) of emergence by an average of 37 and 47% compared with untreated and pelleted seeds, respectively.

Improvement of Surface Sowing in Grassland Establishment : V. Making pelleted seeds with pelleter and its effects on early growth of pasture species

Improvement of Surface Sowing in Grassland Establishment : V. Making pelleted seeds with pelleter and its effects on early growth of pasture species