Macadamia orchards hit by strong winds

The tropical storm Dineo may have a serious detrimental effect on the harvest of macadamia nuts.

A leading independent advisor to the macadamia nut industry, Stephan Schoeman, warned macadamia growers in Limpopo and Mpumalanga about the potential impacts from tropical depression, Dineo, set to hit major growing regions on Thursday afternoon, reports the Lowvelder.

The South African Weather Service says tropical Cyclone Dineo is weaker than forecasters predicted and has now been downgraded to a status of ‘tropical depression ex-Dineo’.

According to the Weather Service heavy rain with strong winds were expected to hit parts of Limpopo and Mpumalanga on Thursday afternoon as a result of the tropical storm. A flood warning has been issued.

The storm affected Mozambique, which has many new macadamia nut plantings, on Wednesday with winds over 100 kilometres per hour and severe rainfall of over 100mm.

The storm, which has been building along the east coast of southern Africa, made landfall in Mozambique on Wednesday night, battering two coastal towns with heavy rain and wind at speeds of up to 160 kilometres per hour. In Inhambane, 500 kilometres north of the capital, Maputo, television footage showed roofs blown off houses, electricity pylons were uprooted and trees sprawled across the streets.

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“More than 100mm of rain in an hour would have a detrimental influence on our orchards causing soil erosion, which would wash away essential organic matter. It’s paramount to replace organic nutrients that may have been lost through compost, husk and chip material,” said Edwin Green, 200 hectare Green Farms Nut Company (GFNC) grower in Mpumalanga and Mozambique.

The 2017 growing season is in its infancy and flash flood rain is the key concern.

“The most immediate infrastructural repercussion is likely to be an overflow of rivers and dams. Pumps, which due to recent drought may have been moved closer to dams, need to be taken out of the flood zone. Overflows must be stable and able to handle the increase flood,” said Schoeman.

“Early season nuts on the ground need to be harvested as soon as possible to prevent losses. Periodic harvesting should continue throughout the next week with ongoing heavy rains expected,” continued Schoeman.

Macadamia nut trees are sensitive to phytophthora, a fungal disease active in anaerobic conditions.

He advised growers to engage specialists to create a treatment plan, especially where extended waterlogging and flood conditions were experienced.

“Recently prepared lands must have adequate runoffs, with clear unblocked drains,” he explained.

Another consideration for growers is potential wind damage.

“Immature nuts may be blasted off trees rendering them unmarketable and trees with poorly developed or unhealthy root systems could be blown over. Where branches tear, it is advisable to treat the wounds.”

“Should winds blow nuts off trees, we will use a well-known method of separating mature from immature nuts using a salt water bath, where ripe nuts sink and the unripe float,” said Alan Whyte, GFNC director and 400 hectare macadamia nut farmer in Limpopo.