Term 1 – Week 6 – Disease, Summer Fruit & Propagation

This week we moved on from pests to diseases. Diseases in horticulture are broken down into 3 categories; fungi, bacteria and viruses. In vineyards common diseases are powdery mildew and botrytis.

Just like in humans and animals, preventing disease is obviously a much better idea than trying to cure it. Possible control methods include:

  • Growing disease resistant varieties
  • Increasing airflow around fruit
  • Irrigate under plants (wet and humidity spread disease)
  • Bring in sheep over winter to clear up any rotten/mummified fruit or leaves
  • Spray fungicides from start of first growth (vineyards spray sulfur every 10 days during the growing season)

Disease can also be spread by insects. The damage they do to the fruit can create entry points for disease to get into the plant.

Plants with diseases mainly need to be either removed totally or pruned back to healthy wood.

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Powdery mildew

On Wednesday we discussed Summer fruit, basically “stonefruit” has been re-branded as “Summer Fruit”, so it’s cherries, apricots, peaches, nectarines and plums. They all belong to the same genus, Prunus. 

To ripen summer fruit you need at least 800 growing degree days a year. GDDs are added up from 1st Oct – 30 April, average temperature each day minus 10 degrees. So if the daily average temperature was 20 ºC, 10 would be added to the GDD total.

The amount of sun will effect the size, colour and flavour of the fruit.

Summer fruit varieties also need enough cold over winter to break dormancy in spring. For example, apricots need at least 1000 hours of chilling (under 7ºC) over winter. This keeps the trees dormant through winter, even if the temperature warms up slightly for a short time. Once they have had their 1000 hours they will start flowering all at once in spring, which is important so all the trees in the orchard are at the same stage at the same time.

Dry conditions are also good for summer fruit. It helps to reduce diseases like brown rot and bacterial blast.

In the afternoon we went out to the cherry trees we planted last winter and did some tree training. This just involves pruning off any unwanted branches and clipping up the rest to the wire to ensure upright growth.

In propagation class we packed up the seed from last week that had been processed and was now finished drying.

 

We also sowed some Sophora microphylla seeds (kowhai). They need to be scarified before being planted because they have a thick, hard seed coat. Scarification involves damaging the seed coat so they can absorb moisture and start all the chemical processes involved in germination. We used sand paper to rough up one little spot on each seed, only a little bit is needed otherwise you could end up damaging the embryo as well as the seed coat. To check if you have done enough you can soak them in water for a few hours and see if they puff up a bit.

 

The kowhai seed we used is from a really old kowhai tree at Northburn. It seems to flower earlier than other kowhai so it would cool if these seedlings end up taking after its parent. I think kowhai take about 7 years to flower from seed so it will be a bit of a wait to find out.

Last week’s weather:

The evapotranspiration numbers have really dropped now, so not much irrigation is needed at this stage.

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Term 1 – Week 5 – Pests, Viticulture & Roxburgh

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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)

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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.

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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.

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Powdery mildew on apple leaves

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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!

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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.

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

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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!).

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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.

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Eucalyptus seed pods

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Eucalyptus seed

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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.

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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!

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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.

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Apples!

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

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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.

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Signage in the packhouse

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

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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.

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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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Term 1 – Week 4 – Plant ID & Seed collection

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Sunset over Alexandra

The weather is definitely starting to turn to autumn. We’ve had a few colder days and nights and deciduous plants are starting to yellow.

This week we continued adding to our plant knowledge and got on with our plant collections. I’ve got all ten plants I need for my specimen book and they are in the press drying out.

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Plants for specimen book

Here’s an example from the specimen collection:

Common Name: Irish strawberry tree
Botanical Name: Arbutus unedo
Family: Ericaceae

Cultural requirements: Full sun, sheltered, well drained soil, neutral PH

Plant description:
Evergreen
Tree or large shrub
Simple leaves, dark green and glossy
Leaf shape is lanceolate with a serrated margin
Inflorescence is a compound panicle, white flowers, flowers in autumn

Identifying features: Red coloured fruit, similar to strawberries. Bell shaped strawberries. Bushy.

Landscaping using / amenity uses: In dry gardens, use fruit in jam or baking, specimen tree

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Arbutus unedo – Irish strawberry tree

We have started a new topic in propagation – seed collection. We went out to Bendigo and collected several different types of seeds; eucalyptus, flax, kanuka.

You can collect seed from nearly all plants. Some easy ones to collect that self pollinate are lettuces, beans, peas, herbs and heirloom tomatoes. You just need to make sure they aren’t an F1 hybrid or you will probably end up with some strange genetic variations.

Phormium tenax (flax) seed pod

Last week’s weather:

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Term 1 – Week 3 – Tractors & Quads

The majority of this week was spent gaining skills on the tractors and quad bikes.

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Claas tractor – the biggest tractor at Bannockburn Rd campus

 

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First time driving the John Deere

 

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On to the next level of tractor

Now I’ve driven all three of the tractors at the Bannockburn campus. The easiest one is the little John Deere. It’s very simple and intuitive. The next step is to get better at using the bucket and then towing implements, such as a sprayer or mower.

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Ryu mastering the quad bike

Riding the quads was a lot of fun once I got the hang of them. We went out to the motor track and had a great afternoon racing around. The quads have a roll bar installed to add some protection, otherwise they can be pretty dangerous.

 

Weather – Hot and sunny! We’ve had a last little bit of summer before autumn hits.

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Does this tree really think it’s already autumn?! Taken at Lake Hayes

Last week’s weather:

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