The grape harvest got off to a difficult start this month as farmers estimate losses of up to a quarter of their yield due to the heat and this year’s dry, warm winter.
As the country faces its third summer heatwave, Gerald Vella, administrative secretary of grape producer cooperative Vitimalta said the extreme temperatures were causing berries to shrivel and burn.
“The last three to four harvests were really bad,” he said.
“So far, we think that we have lost 25 to 30 per cent of the usual weight and we’ll have to wait and see if it gets worse because the harvest will continue until September.”
Vella said the losses were terrible for grape farmers because they had already been dealing with dwindling yields over the last four to five years, due to ageing vines as well as climate change.
“It is becoming less and less financially sustainable for us to work,” Vella said.
“We get paid by weight, and we’ve been enduring lower yields due to low rainfall and higher temperatures in winter, as well as the age of the vines.”
Vines need warm summers and long hours of sunlight, but cold winters in order for them to enter a dormancy period and “rest”, the cooperative official pointed out.
The mild winters over the last few years “stressed” the plant, and the damage was compounded by drier conditions and difficult summers.
One of the effects of strain on the vines was that the plant did not absorb water efficiently, Vella said.
“You can compensate for the shrivelling of the berries due to excessive heat by giving the plant water. The problem is that when the plant is really under stress it does not function properly and does not absorb the water,” he said.
And yet another issue was that grape farmers were having problems applying the organic fungicide, sulphur, on their plants to treat mildew (a thin whitish fungal coating), since in hot and very high temperatures it burns leaves and grapes.
Regarding the burnt and shrivelled berries, Vella said that the biggest impact was on those grapes exposed directly to the sun.
While the vine canopy prevents damage to the berries from direct sunlight, it is pruned to allow better air circulation to prevent fungi setting in.
“Vinegrowers need to strike a balance between protecting the vines from fungus and protecting the berries from the sun.
“This time the problem was that we did not know how hot it was going to get,” Vella said.