Wet weather heightens anxiety about kiwifruit disease

Kiwifruit grower Neil Treblico is playing a waiting game to see how much the vine disease Psa impacts on his crop this seaso. Photo/file

Kiwifruit growers are nervously waiting to see what impact the wet winter and early spring has had on the emergence of the vine disease Psa.

Grower Neil Trebilco of Whakamarama said Psa thrived in wet conditions and there had not been enough spells of fine weather.

"We have not sprayed as much as we would have liked because it has been so wet."

MetService forecasts held little relief for Bay orchardists and farmers, with unsettled showery weather until next Wednesday when it cleared for a couple of days, only for showers to return Friday and Saturday.

Looking further ahead, Meteorologist Peter Little said the trend to mid-October would be for less than normal rainfall and temperatures returning to normal.

January to September had been the second wettest for Te Puke since records began in 1958.

Mr Trebilco said the other problem for lower lying, less well drained, orchards was ground conditions, with machinery getting bogged down.

He knew of an orchard that had to tow out its fertiliser spreader sometimes after it got stuck.

Mr Trebilco said the threat from Psa mitigated against what had been an excellent bud burst for most growers because of the winter chill.

However, it was too early to tell what impact Psa would have on vines this season. "We will have to wait and see as we move into spring."

A vine infected by Psa caused flower buds to drop, with the green Haywood variety affected more than the replacement Gold3 variety.

"From our perspective, we have not seen anything untoward yet, but it is hard to know."

New Zealand Kiwifruit Growers chairman Doug Brown said ideally, growers liked a warm spring and plenty of sun.

"We are at the mercy of the weather gods."

He was hearing reports that there was a bit of Psa around. "It is expressing itself, but it is still a bit early to assess how bad it is."

The longer period of damp weather was ideal for Psa and the sooner they got into drying sunshine, the better, Mr Brown said.

Applying the sprays depended on the weather and the level of Psa on each orchard. "It is pretty much an individual thing."

If they got the sprays on in winter, the levels of Psa would not be as high in spring. Most Bay of Plenty orchards had some level of Psa, he said.

Zespri's chief operating officer Simon Limmer said it was very difficult to say what impact Psa would have because it was still very early in the season and a long way from harvest.

So far it had been quite good because of the higher bud burst although the rain had impacted on spray programmes.

"Spring is the time when Psa shows its colours."

Growers went through a nervous time in September and October when the symptoms of Psa showed. "Every season is different."