Term 1 – Week 5 – Pests, Viticulture & Roxburgh


This week we started a new topic looking at pests, diseases and disorders that can be problems in horticulture and viticulture.

Pests include: aphids, codling moth, mealy bugs, phylloxera, mites, leaf-roller caterpillars
Diseases: botrytis, powdery mildew, black spot, leaf blight, rots, blast
Disorders: climate issues (hail, wind, frost), nutrient deficiencies, poor management (herbicide damage)


Codling moth damage (caterpillar stage)

Orchards and vineyards need to have plans in place to check for and to manage pests and diseases. Wayne’s advice is “what you don’t see you will get”. So if you’re not checking for something properly (and therefore not controlling) it will likely get out of control and run riot through your orchard. Wayne also pointed out that if we spotted any really fast moving insects, these are probably predators and beneficial insects.


Orcharding legend, Wayne, with a Light-brown apple moth trap

Jackson’s Orchard have traps for certain types of insects to monitor their numbers. They attract the bugs with a pheromone. One trap is for the Oriental fruit moth. Luckily that has not been found in New Zealand yet. If it is found it would basically shut down fruit exports from Central Otago.


Powdery mildew on apple leaves


Grape vine leaves infected with a virus

On Wednesday we were out at the Bannockburn Rd vineyard checking how ripe the pinot noir grapes are. We collected a few bunches of grapes at random throughout the vineyard, smushed them up and tested how much sugar was in the juice with a refractometer. Sugar levels are measured in brix. Pinot noir should be about 23 – 24 brix at harvest. If they are being used for bubbles it can be less. Our grapes will need another few weeks. Hopefully we don’t get a bad frost before then!


Testing grape sugar levels

After testing the sugar levels we went out and did some green thinning. This means cutting off the grape bunches that are still green and won’t ripen in time.


Left: nearly ripe grapes on the vine. Right: discarded grapes


Bird damage despite the nets. 

I ate some of the nearly ripe grapes and they are pretty sweet already (not as many as the birds, promise!).


Bring on harvest!

On Thursday we started processing the seed that has been collected. This meant a lot of work with a sieve! Then drying and storing the seed.


Eucalyptus seed pods


Eucalyptus seed


Muehlenbeckia astonii (wiggy-wig) fruit with black seeds

I was quite taken with the wiggy-wig fruit and seeds that looked like little white flowers.

On Friday we headed off to Roxburgh on a field trip. There’s a huge blueberry grower there that we stopped to see (15 hectares). That was really interesting, I didn’t know much about blueberries before other than that they need an acid PH soil. They add wood chip as a type of mulch to bring down the level to below 5.5.


Blueberry bushes – high bush variety

The main issues they have are pollination at flowering and weeding. Blueberries need a lot of help pollinating. They bring in 90 hives of honeybees and as many bumblebee hives as they can get. To get the ideal size blueberry each flower needs 6 visits from a bee. Unfortunately blueberry flowers aren’t bees favourite, so that might not happen especially if there are more interesting options for the bees!


A few berries left after harvest

As far as weeding goes, they do use some sprays, but mainly it’s done by hand. Over the winter they employ 3 people full time just to weed. They indicated it would be quite easy for them to go organic here in Central Otago but their parent company  is concerned that doing that would devalue their blueberry orchard in Hawke’s Bay as they wouldn’t be able to go organic.



Next we went to the massive apple packhouse in Roxburgh. It’s a pretty high tech operation just to process apples!



The machine takes 18 photos of each apple (at super speed, this conveyor belt is moving fast) and shoot it out down the slot with all the size and colour apples to be packed. These ones that are being nicely packed and arranged are going to be exported.


Signage in the packhouse

Local market, however, isn’t quite as flash:


Although, local market product doesn’t need all the sprays (pesticides, fungicides etc) that the export product does. Apparently Asian countries don’t care what sprays have been used but one hitchhiking insect can mean a whole shipment is rejected, whereas Europe is more concerned about the chemicals.


Fog along Lake Dunstan from Clyde to Cromwell

Temperatures have dropped and trees are on the turn. We’ve had some really clear sunny days that have warmed up in the afternoon, but it has been quite chilly in the mornings now.

Last week’s weather:



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