Thursday, 12 March 2020

Warding off Jack Frost- Cromwell

Catch-up (early October, 2019)

After I'd completed my mega road trip from Winton to Cromwell & Lawrence return, to photograph the fruit blossoms, a photography acquaintance mentioned that I should do the trip again, at least to Cromwell, to take photos of the blossoms after the frost protection sprinklers were switched on in the orchards. 

Sunrise over Cromwell
How do frost protection sprinklers work? Coating a tree or vine with ice to protect new buds & blossom from frost may seem counter-intuitive but there is a science behind it.

Overhead low pressure sprinkler systems provide a high level of protection, the key is to form clear ice on the plant. Sprinklers deliver just enough water to glaze the plants in layers of ice, rather than soaking them and forming one massive layer of ice that may cause more cooling before it freezes.

Clear ice means that an endothermic reaction is taking place and the warmth of the plant is being trapped inside it. If the ice starts to become cloudy, the plant is losing heat and that’s when damage can occur. Water spraying starts well before the frost forms and continues until after the ice has completely melted from the trees. If water stops spraying on the clear ice, it goes from being endothermic to exothermic, and the heat loss and ice can then damage the fruit.

Drive back to Cromwell? 'What a good idea', I thought, the seed was planted. It would mean a 4am start to cover the 200+km from Winton to Cromwell but I was up for the challenge. Like a hoar frost, iced blossoms had been on my 'must capture' list for awhile, I'd just never been in the right place at the right time. Now was my chance. 

My friend had access to a Cromwell orchard's temperature gauge and he informed me by text late one evening that there was a predicted frost the following morning and I should be ready to go.

It turned out to be a very light frost and the sprinklers weren't needed but thankfully he was able to text me before I had left Winton. The next time I heard from him was a week or so later but unfortunately we had left Winton and were exploring the Milford Road by then, so I missed out again.

But as luck would have it, and after our short visit to Mavora Lakes, we were unexpectedly back in Cromwell parked in the NZMCA Park at Lowburn when very early one morning, around 3am, I woke with start to a very loud noise filling the air.

Once I figured out where I was- you get that when you're constantly on the move, it's sometimes takes a few moments to visualise where you're parked and in what direction you're facing- I realised that I could hear wind turbines and helicopters roaring into action, preparing to fight off a frost. 

How about that! I had no need to drive 400km this time, I was a mere 4kms down the road from the orchards! I was ready to go and out the gate well before the sun came up. The first orchards were still in darkness but I could hear the soft click, clack of the sprinkler heads turning and the gentle patter of water falling through the trees to the ground.

I carried on to the far end of Cromwell and then around onto a back road; sprinklers swishing back & forward everywhere I looked, a helicopter down very low in one orchard, weaving back and forward along the ends of the rows and the roar of wind fans and turbines in others.

All three methods obviously work but I'm not too sure how the orchardists decide which is the best way to go; sprinkler systems seemed to be most numerous.

Perhaps it's money, helicopters would cost a fortune, maybe there isn't access to water or perhaps the wind turbines can be shifted around the orchard more easily.

I had overlooked one major difficulty which now seems rather obvious. I was soaking wet within minutes of getting out of the ute- even with a rain jacket & gumboots on.

It didn't matter that I was ducking in and out of the passing overhead sprinkler trying to shoot a blossom before the sprinkler passed over again because if the sprinkler next door didn't get me the neighbour on the other side would. They were all out of sequence. 

Luckily I had an extra jacket in the ute and there were a couple of large towels packed into the back seat. I used one to cover the seat as I was climbing in and out in my wet gear all the time and the other one to wipe down my camera and dry my hair! I looked like a drowned rat. 

I was a little worried about my camera though, it's weather proof but not water proof and also, as I was zooming my lens in and out, water was tracking inside the lens.

Later when I arrived home and had dried my camera and lens out as much as I could, I left them on the bed in the warm sun to dry them out. I opened the window a little so any water would evaporate rather than condensate in the warmth. It worked although it did take a few hours each day to get rid of the moisture. Next time I need a waterproof cover for my camera.

After flitting back and forward through town and up and down down many of the back roads chasing sprinklers and easy to access orchards, I stopped at the Wooing Tree Vineyard, right in the middle of town. The sprinklers were also working overtime here and... River Rock Estate, a little boutique winery across the road...

...where I managed to do a few close up shots...

...without getting drenched as I could keep outside the sprinkler's reach. 

Then with the sun climbing higher, the ice melting and enough blossoms photos to sink a ship, I thought I might just add a few more before I headed home. 

I'd passed this row of beautiful old crab-apple trees numerous times during the last couple of hours, now I stopped to take some photos of the gorgeous blossom.

Never satisfied and always striving for better photos, I can't wait until the next frost event. If you're passing through Cromwell next spring and you spot someone with a camera, ducking & diving around the fruit trees on the edge of an orchard covered from head to toe in ocean going wet weather gear, you'll know who it is! 


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