Risky not to test home-saved seed

2 January 1998

Risky not to test home-saved seed

Farm seed savers tempted

to cut costs further by not

having their seed tested and

dressed could be skating on

very thin ice this spring.

Brian Lovelidge reports

THE soggy 97 June left a legacy of potential disease problems which, if ignored, could cost growers using their own seed dearly, warns Malcolm Williams, Midland Shires Farmers.

For the same reason he strongly advises growers buying certified seed to have it dressed. "The cost, generally about £10-20/ha (£4-8/acre) for cereals, £4-35/ha (£1.60-14/acre) for peas and up to £17/ha (£6.90/acre) for beans, will be recouped many times over through better establishment and vigour, he contends.

Mr Williams reckons 25-30% of the cereal and pulse seed and 10% of oilseeds drilled this spring will be farm-saved. But only 60-70% will be tested for pathogens and dressed, leaving a lot at risk from seed-borne diseases and pests.

Processing cereal seed without prior testing is almost as bad as not having it dressed, he maintains. That is because the co-operatives tests show fusarium threat is the worst for many years with infection levels in wheat and barley seed as high as 80%.

The reality is that dressings cannot completely control the disease when over 30-40% of seed is infected. So seedling losses may be unacceptably high if seed-bed quality is less than perfect, warns Mr Williams.

"Septoria nodorum levels on spring wheat are also much higher than average – up to 20% – due to the wet June.

"For the same reason many pea and bean seed samples carry high levels of ascochyta."

All wheat seed dressings control reasonable levels of fusarium and Septoria nodorum and all barley dressings control fusarium.

MSF is using Beret Gold (fludioxonil) and Sibutol (bitertanol + fuberidazole) on wheat this spring at about £43/t and Raxil S (tebuconazole + triazoxide) for barley at £47/t. Other dressings with similar control spectra cost more or less the same. If growers want the extra benefits of Baytan (fuberidazole + triadimenol), it costs about £90/t.

Pulses & oilseeds

The co-operative rejects pea seed samples with over 2% ascochyta. But good control in its seed crops means only one sample has tested positive. As a result the seed has only been treated with the cheapest dressing, Thiram at £18/t, which controls damping-off. The Rolls-Royce product, Apron Combi (metalaxyl + thiabendazole + thiram), costing about £125/t, is vital if the land has a history of downy mildew, stresses Mr Williams.

"We have heard of pea seed with 5% ascochyta infection. Unless such samples are treated against the disease it could depress yield by as much as 25%."

Generally beans receive no dressing. But with this seasons high ascochyta risk it will probably pay to use one like Hy-Vic (thiabendazole + thiram) at £68/t, he suggests. For protection against damping-off alone a Thiram dressing at £28/t.

Growers rarely have a choice of dressing for oilseed rape seed, he notes. It is essential to apply one against flea beetle which can severely damage emerging crops. This season the risk of seedling loss through alternaria could be higher than normal. Lindex (fenpropimorph + gamma-HCH + thiram) and Vitavax (carboxin + gamma-HCH + thiram) are the most widely used products, but Vitavax does not control alternaria.

Linseed seed also tends to be routinely dressed as it invariably carries a significant disease burden and is at high risk from flax flea beetle, adds Mr Williams. The emerging crop is also very prone to damping-off so control with a seed dressing is very cost-effective.

Processing peas being drilled in east Kent. Seed-borne ascochyta disease could be a problem unless the correct seed dressing is used.