19 March 1999

Maintain a close watch out for signs of eyespot

EYESPOT risk is high this year. So start checking wheat crops now, and dont rely on just one inspection to make your spraying decision, warns Bill Clark of ADAS Boxworth.

"The weather conditions have been ideal for eyespot and take-all inoculum is around, too. Taken together that could mean big yield losses."

Yet very few growers check their crops often enough to truly assess the risk, believes Dr Clark. "There is no correlation between the amount of disease found early in the season and final eyespot levels, so its important to keep looking."

Growers should check at GS30/31 and again at GS32. Then go back at the end of the season to assess how well the chosen treatment performed, he advises.

But he admits that identification is not easy. "Once lesions have been spotted on the base of the stem, pull the leaf sheath off to see if they are penetrating. The ADAS threshold of 20% of tillers with penetrating lesions is a good spray guide."

Dr Clark sounds a note of warning if take-all is present. "The combination of take-all and eyespot is much more serious than either disease alone, so use a lower threshold if this is the case."

ADAS/Novartis eyespot surveys conducted over the past three years prove just how difficult growers find it to identify the disease, adds Dr Clark. "In 1996, which was the worst eyespot year for 20 years, over half of the fields surveyed were over the threshold. But only 7% were treated.

"There was a similar picture in 1997 and 1998, only fewer fields were over the threshold. Often the wrong fields are treated."

Average yield loss to eyespot over the three seasons was 8%. "But losses in individual fields can be up to 35-30%."

Dr Clark says that both W and R type eyespot are found in the UK. "Triazoles have selected for rye types but there is a mixed population in the field.

"The R type is slow growing and tends to infect later, but it can be very aggressive. It is quite common to find both types on the same plant and the same lesion."

He advises using flusilazole (Sanction) and epoxiconazole + kresoxim-methyl (Landmark) on the W type and prochloraz (Sportak) and cyprodinil (Unix) on both W and R.

"Cyprodinil has shown very good activity and it is the best product in moderate to high-risk situations."

The final decision on spraying has to be made at GS32. "After that, the crop gets too dense to get the product down to the stem base. So walk the fields, look for lesions and consider variety and weather conditions. But check two or three times, or risk missing a late infection."

Field walking is essential, stresses David Kirkham of Notts-based Fieldcare. "Eyespot is almost a hidden disease, so it has to be looked for.

"And infection can change rapidly in the field. In a dry period, it might only penetrate the outer leaf sheaths, which then die, so the disease is naturally arrested. But if its wet, the disease can suddenly appear in fields which were clean earlier in the season."

Growers with an eyespot problem must accept the extra cost of treatment, Mr Kirkham adds. "In a high risk situation, a 0.7kg/ha spray of Unix will cost around £22/ha. At lower rates, says 0.3-0.4kg, it allows you to bring in a partner product for foliar disease." &#42

Future for SW spuds set fair

potato growers in the south-west are set to benefit from the need to reduce costs between farm and supermarket shelves, says Branston Potatoes chairman Chris Howard.

Speaking at an open day to show off new intake, grading and packing facilities at Branstons Somerset packing station, he said costs from farm to shelf were about £100/t, half going on transport.

With Branstons Somerset plant just 60 miles from Tescos biggest depot at Southampton that gives south-west growers a bright future. The area has all the ingredients needed for quality potatoes, he added, with suitable land, ample water supply and good management.

But just 65% of the plants throughput currently comes from Branstons SW producer group. Other growers and imports from the West Midlands and Lincs are needed to plug the gap. Branston wants more potatoes grown in the south-west, preferring expansion to come from existing growers taking on more area, said Mr Howard.

He was scathing about letters in the farming press attacking supermarkets. Tesco had provided profit and growth and paid its bills on time, he said. It had helped build the business from nothing to an annual turnover of £40m.

Supermarket quality initiatives had also made British potatoes the most highly respected in the world, with 115,000t a year exported.

"A lot have forgotten the old days of the potato merchant who sometimes paid, always a bit less than had been agreed and whose idea of marketing consisted of providing a pile of un-named sacks." &#42

Home-save seed use

About half of Branston Potatoes Somerset producer group used some home-saved seed this year, says company agronomist Paul Bibby.

"There was no aphid here last year, probably due to the cool summer and absence of large areas of oilseed rape and sugar beet in the area. And in any case they all had their seed tested for Y and X viruses."

Seed supplies and prices have eased recently as more Scottish crop is graded out. Typical prices are between £300/t and 450/t. The biggest demand is for Estima and Marfona. Fianna, Saxon, and Desiree are also wanted.