24 July 1998

SAVEDSEED? GETITTESTEDORRISKLOSS

If you are planning to save your own seed this autumn,

get it tested. Failure to do so could jeopardise the entire

crop. Edward Long visited NIAB to find out more

THIS autumn more home-saved cereal, rape, bean and pea seed could be sown than ever, as growers look to cut costs. But if better returns are to result seed must be tested to ensure yield and quality are not jeopardised.

That is the message from NIABs Official Seed Testing Station at Cambridge, which checks farmers own stocks as well as seed produced under the official Certification scheme.

The wet season has led to higher than normal disease pressure, so home-saved seed will need checking to ensure the best possible result in the field.

In response to grower interest in farm-saved seed NIAB is offering a package of tests under the Labtest banner. "Farmers using certified seed know its quality is guaranteed," says NIABs Juno McKee. "There are no guarantees with farm-saved stocks.

"To protect against drilling trouble for the future it is important to have home-grown seed tested. It is very easy to slip up using poor or diseased seed, and mistakes can be very costly.

"This is why we are offering our Labtest packages which pull together the main needs for the main arable crops. They have been designed to be cost-effective and offer significant savings over the individual tests. Because they are flexible, farmers can negotiate a pick-n-mix deal tailored to suit individual needs."

&#42 Wheat and barley

The germination test is the bottom-line requirement for a good crop. If some grains are non-viable due to disease, pre-harvest desiccation damage, mechanical damage or cooking during drying, the crops potential is compromised before drilling.

Results from samples checked by NIAB show what can happen. Last year 7% of wheat failed to reach the EUs minimum standard of 85% germination. In the previous year 8% failed to make the grade, with 2% showing less than 50% germination.

Barley seed is more susceptible to upset germination. In 1995/96 21% of samples were below the 85% threshold level, and 13% below 50%.

"With the push towards lower seed-rates it is critical to use good seed," Dr McKee stresses. "Cereal growers may think they can do their own germination testing, but the conditions must be just right and assessment standardised. It is easy to be fooled."

A seed may appear to have germinated, but there could be something wrong with the seedling, she explains. "We can spot abnormalities which would not produce healthy plants in the field."

The percentage germination together with thousand grain weight of seed are needed to calculate accurate seed-rates. Both are included, together with a sowing rate table, in the basic NIAB Labtest package for £40. Test results are usually available within 7-14 days.

For £147 a comprehensive package, which includes the basic service, plus viability and vigour tests and checks for seed-borne disease, is offered.

NIABs viability test, which provides rapid back-up for the germination test, involves soaking 100 seeds in tetrazolium salts which stain living tissue red. Trained analysts can quickly detect which will not grow. Results are available in 1-3 days. If they show the sample has less than 70% viability other tests will be cancelled and the price reduced to £60.

Under difficult seedbed conditions even viable seed with high germination can fail to establish properly. The vigour test picks out low-vigour seed, which would probably not survive adverse conditions and may fail to produce vigorous seedlings even under the best conditions, so it can be discarded.

The disease scan detects fusarium and bunt on wheat, and loose smut, leaf stripe and net blotch on barley. It is geared to helping growers decide whether to apply a seed treatment to control these preventable diseases.

"Last year 74% of farm-saved samples checked contained greater than 5% fusarium. But with a good seed treatment the bulk of them could be used," says pathologist David Kenyon.

"After another wet June and high levels of infection in crops we expect to find high levels on many batches of farm-saved seed this year. But where a well-timed ear-wash fungicide goes on grain should be relatively clean. "There is always an undercurrent of bunt, there was more last year than normal, so there is always a risk of sudden flare-up."

Dr Kenyon has seen little barley leaf stripe or loose smut over the past two seasons. He is concerned by high levels of net blotch in this seasons crop and says it will be important to weed out samples with very high seed- borne infections.

"Cereal growers should always be alert to the possible dangers of sowing infected seed and ensure it is clean to start with, or receives appropriate treatment. Home-saved seed from a crop grown from bought-in seed should be reasonably healthy, provided a good fungicide programme was used. But checks are still essential. Risks may increase with successive generations of farm saving if testing is not carried out."

Labtest reports strengthen grain quality assurance by covering the seed, he notes.

&#42 Oilseed rape

FARM-SAVED rapeseed must pass a glucosinolate test before area payment can be made. Last year 15% of samples analysed by NIAB were above the 18micromole/g cut off.

Anyone saving rapeseed must get glucosinolates checked, or risk being left to pick up the pieces afterwards, warns NIAB chemist Jon White.

Some varieties are better prospects for farm saving than others, he says. Although Apex comprised 56% of samples last year, others such as Arietta, Capitol and Alpine showed a higher pass rate.

The glucosinolate test is included with the germination test and thousand-seed weight count in NIABs basic package for £48.

"The viability of rapeseed can easily be harmed by poor desiccation or drying and it is particularly vulnerable to mechanical damage," Dr McKee explains. "If lower seed-rates are used anything that upsets germination can have a severe impact on the crop.

"Home-saved seed is cheap so a poorly emerged crop can be re-drilled. But this causes delays and the job can clash with other operations. There is also the risk that lost seedbed moisture could rule winter rape out altogether."

NIABs full rape testing package costs £160 and also includes the viability and vigour tests plus a search for sclerotinia, alternaria and phoma.

"The last two tests are particularly valuable after a wet late season when infection on seed may become significant," says pathologist Dr Jane Thomas. "Seed-borne alternaria can kill seedlings, or cause early spotting on young plants which act as a reservoir for infection later in the year."

Samples failing the viability, vigour or glucosinolate tests will not be checked for disease so qualify for an £80 rebate.

&#42 Peas/Beans

SEVERE disease pressure means a comprehensive test is likely to be needed for anyone planning to save pea or bean seed this year.

The basic germination test with thousand seed weight assessment and a sowing rate table costs £30 for peas. The more comprehensive deal, which costs £92, includes a vigour test and check for mycosphaerella and ascochyta.

Mycosphaerella leaf and pod spot likes wet weather – if it establishes early it can reduce a population, later infections knock yield. Ascochyta can also deplete populations, surviving plants can carry infection through to later in the season. Where 5% of peas in a sample are infected NIAB advises use of a seed treatment.

A third bolt-on, which includes a blight test, costs £152. As there are no seed treatments or foliar sprays to control the damaging pea bacterial blight, which is particularly severe in the winter crop, use of disease-free seed is the only worthwhile avoidance measure available.

Growers intending to use home-saved winter peas are urged to request the test as 63% of samples seen last year were infected.

Large bean seed is highly vulnerable to mechanical damage at harvest so germination can be hard hit. Last year 43% of samples tested were below the 85% minimum for bought seed, and 3% failed to reach 50%. In the previous year 57% were under the 85% minimum. NIAB has seen one lot with just 4% germination.

The basic package for field beans costs £67 and also includes a check for ascochyta. "The disease is rampant in this seasons crops and both the most widely grown varieties, Punch and Target, are susceptible," Dr Kenyon points out.

"As a high proportion of bean seed sown each year is home-saved, it must be checked, as even low levels of seed infection on a susceptible variety in a wet autumn can cause severe disease with up to 15% yield loss."

Where stem nematode infestation on seed is likely – wet weather favours it – an optional extra test can be included for £15. Every year NIAB sees some stem nematode infested – last year 11% was infested. &#42

BASIC LABTEST

&#8226 Germination %.

&#8226 1000 grain weight.

&#8226 Sowing rate table.

&#8226 100g sample required.

&#8226 Results in 7-14 days.

&#8226 Cost £40.

Malting barley

Malting barley growers planning to use their own seed are offered a Labtest package which includes the basic checks on germination and TGW, plus varietal purity and a plot test where the sample is grown at Cambridge and checked in June.

Sample size is 500g with purity results available in 7 days and germination in 7-14 days. Cost is £96, plus £81 for seed-borne checks.

COMPREHENSIVE LABTEST

&#8226 Basic Labtest, plus:

– viability & vigour

– seed-borne diseases

&#8226 Sample size 350g.

&#8226 Results: 1-3 days

viability/vigour

1-8 days disease checks

&#8226 Cost – £147.