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Weather and disease tech tools help Whanganui grower succeed in all seasons

Whanganui-Manawatu isn’t as well known for kiwifruit as some other parts of New Zealand, but with a little help from technology, local orchardist David Wells is finding a way to thrive.

The orchard he co-owns at Ngaturi, east of Whanganui, is managed by Apata Grow. It includes 20 hectares of Hayward green kiwifruit vines, 3.5 hectares of which was planted in 1978 and the remainder in 2020. The location at the confluence of the Mangawhero and Whangaehu rivers has its own microclimate featuring cool winter and hot summer temperatures. The average annual rainfall is a relatively low 900 mm, and while the region has experienced major flooding – most recently in 2004 and 2015 – Wells’ orchard is beyond water levels reached in those events.

He recently installed a Harvest Weather Station on the orchard, providing him with real-time local weather information to aid decision making. The weather station includes wind, humidity, evapo-transpiration and rainfall sensors, along with sensors in the earth that provide readings for soil temperature and moisture levels.

The information from the weather station is fed into the kiwifruit industry’s Weather & Disease Portal – a valuable tool developed by New Zealand agri-tech company HortPlus that combines weather station data with disease risk models to provide graphs and information orchardists use to make key decisions. The portal is freely available online to all growers and is run by Kiwifruit Vine Health and Zespri.

For Wells, the weather and disease data and daily email report generated by the portal provides information he uses to make decisions on irrigation, Psa control measures and frost protection – the latter provided by four windmills.

“Basically, I’m a bit of a weather nut,” he says. “I’m particularly interested in the chill units and Psa risk model on the Weather & Disease Portal. I’m also the KVH co-ordinator for Whanganui region, which provides further motivation for my interest in the portal.”

This year’s weather has been more challenging than most, with extreme weather pushing orchard management to the limits.

“La Niña has typically helped us by keeping temperatures warm and the westerly winds away. Uncharacteristically, the last two La Niña summers have seen much higher rainfall than normal - this year 500mm fell in just the first two months. Unfortunately this has highlighted small pockets of the orchard where drainage is not so good and vines showing signs of moisture stress.”

He says two seasons ago Psa bud rot took out approximately 75 per cent of the flower buds in the old producing block. However, the same block bounced back well the following season, producing more than 13,000 trays per hectare.

“We seem to be a bit more susceptible to Psa where we are, perhaps because of the cooler weather. This year we have quite a good crop in the older vines, presumably assisted by timely trunk girdling. However, the girdling option is not available for the younger vines where we have lost virtually all the flower buds to bud rot and there have also been losses of young vines to Psa.

“I’m trying to do all I can to manage the risk and the weather station and Weather & Disease Portal are part of that.”

The data from the Harvest Weather Station on his orchard was used as part of a one-year Zespri project to connect ten on-orchard grower weather stations to the Weather & Disease Portal to gauge the difference localised weather data could make for orchardists. Wells’ orchard was an ideal candidate because of its distance from the nearest regional weather station.

“There are often quite big differences between the readings. Our nearest station in Waitōtara was recording wind gusts of up to 60 km an hour during Cyclone Gabrielle but things were lighter here - our on-orchard station recorded maximum gusts of 25 km an hour.”

Wells says there is great potential for orchardists to make more use of technology in their operations, and to harness localised weather data and decision-support tools for better Psa management.

Tools like the online portal allow orchardists to use more data in their decision-making – they allow them to do what they need to at the right time, rather than continuing on with what they have always done or what they always haven’t done.

“This winter and spring I will be watching the portal and communicating with Apata. I’m going to make quite sure that if we see something coming that we carry out early treatment.”

He says access to weather and disease data has the potential to help increase an orchard’s productivity. Having an on-orchard weather station makes the data more powerful and supports localised decision-making.

“The technology seems to be constantly improving,” he says.

Aerial show of the orchard at Ngaturi