Peach tree crop failures

The difference between 2013 and 2014 peach harvests has been inexplicable; from boom to bust with a vengeance. With five peach trees on the property, we’ve had not a single peach reach the kitchen. What’s gone wrong?

Some peach trees fall into a boom and bust rhythm, especially if allowed to crop too heavily in any particular year - they respond by boosting vegetative growth in the following year. But that would not explain total failure among both early and late varieties that are naturally out-of-sequence with each other.

The clue came a few weeks ago in a public talk at the Rare Fruit Society by Graham Brookman from the Food Forest; the winter of 2013 was much warmer than the long-term average and the peach trees had not clocked up their requisite ‘chill hours’. I hadn’t registered that myself, as we’d been off on the annual pilgrimage to Germany last July, enjoying the northern summer while the garden should have been shivering its way through the coldest month of our year. I did come home to experience Australia’s warmest September on record.

So what are ‘chill hours’, and what will a lack of them mean in a warming climate?

Peach trees are deciduous and so build their buds during summer before dropping their leaves to over-winter. These buds will develop either into fruit or leaf clusters during the following Spring but face the risk of breaking dormancy during a warm spell in winter, only to be ‘burnt off’ by a following frost. So to protect their buds against freezing winter temperatures and this danger of waking up too soon, stone fruit have developed ‘clocks’ that must ‘tick off’ a certain number of chill hours between 0⁰C and 7⁰C (32F and 45F) during the winter months. In the case of our peach varieties, we need around 500 chill hours for proper leafing and fruiting; Graham stated that we had fallen well short of this in the winter of 2013.

One’s local climate sets what fruit trees will and won’t work. Here on the Adelaide plains, it’s hit-and-miss to grow apples, cherries, kiwifruit and other high-chill varieties. Stone fruit such as apricots, nectarines and peaches are usually solid performers unless we experience an unusually warm winter, as we did last year. Shifting to ‘low chill’ varieties is a long-term strategy; solid advice from a local nurseryman is advisable before finding space for fruit trees in a backyard garden.

In the long-haul, climate changes will magnify this same problem over far larger growing districts, making fruit supply to urban populations that much more uncertain and expensive.

Autumn garden tour 2014

The autumn equinox is upon us - day and night are the same length of 12 hours - as southern Australia slides gently towards winter while the northern hemisphere Spring commences. Summer crops of tomatoes and capsicums, basil and zucchini, climbing beans and pumpkins, cucumbers and eggplants are being harvested, while winter crops of cabbage, leek, broccoli and kale are coming off the seed table and entering the still-warm soil.

It’s been a harsh southern summer, and to have brought the garden through these extremes has taken even more effort and care than usual; someday soon the water bill will turn up and is likely to be approaching $1000 for this last quarter and this huge garden.

On the positive side of the slate, some of that expensive water has brought the citrus and banana crops through the summer in good order; they are ripening and healthy rather than marked with that weariness of trees water-stressed for too long.

We grow rows of basil plants for pesto which we freeze and eat throughout winter; this past summer’s crop has also been healthy and productive despite the heat. Chopped basil leaves over sliced tomatoes and bocconcini cheese make a pleasant addition to lettuce, capsicum and cucumber salads with our main meals.

 

 

 

 

 

The surprise runner this year is the early autumn garden developed after an unexpected rainfall of 111mm (4.3”); here Chinese cabbage, five varieties of dwarf bean, spring onions, lettuce, broccoli, late zucchini and cucumber crops are growing well in the cooler shoulder season.

In among the rarer vegetables in this garden, ‘Triamble’ pumpkins are maturing, delicate ‘Purple Tiger’ chillies are adding beauty, ‘Lazy Wife’ climbing beans are producing at last in the cooler conditions and ‘Chocolate capsicums’ (peppers) and ‘Freckled Cos’ lettuce add novelty to our salads.

Regular Butternut pumpkins coexist with the Triambles without cross-fertilization; they are different species.

Coffee (‘Arabica’) bushes and comfrey share a spot in the orchard, chestnuts are ripening, Willemette raspberries are producing a small autumn flush and German filderspitzkraut cabbages are coming along on the seed table beside lettuce, leek and Italian broccoli.

The floor of the orchard – turned over and fertilized this past month by the scratching of the hens – has been raked and free-seeded with silverbeet and bulk lettuce seeds that are so abundant in a seed-saver’s garden. When the rains pick up, these green plants will provide further food for hens and humans.

Sadly, its been a totally unproductive year for the many peach trees scattered over the property; there were simply insufficient ‘chill hours’ of cold temperatures during the previous mild winter to set fruit properly this past spring.

In the shed, boxes and tubs of seed heads are starting to accumulate; lettuce, sunflowers, cucumber and silverbeet will soon be dried off and tinned for next year’s crop.

Down the back of the production garden, the last of the summer zucchinis flank the bed of ‘clucker tucker’ being grown for chook feed.

Cabbage wars

I try to get all of the winter crops from the Brassica family – cabbages, sprouts, broccoli, cauliflower, turnips and kale – out of the garden before summer starts in order to break the life cycle and to kill off ‘white fly’ (Aleyrodids) infestations. However, I’d left the Red Russian Kale in one of the farther beds to run to seed to restock my collection, so I’ve been expecting trouble.

So it was no big surprise to see our only summer-grown cabbage ‘Red Dutch’ suddenly infested. However, the usual air-borne swarms seemed to be missing, so I had to go up to the house to get my glasses and camera before the microscopic evidence revealed something else again.

Aphids!

I have so little trouble with pests and diseases in this organic garden that I’m unprepared for these attacks; I don’t even keep the allowable white oil or pyrethrum sprays on hand.

There are a couple of things I could try; turning the chooks into this bed will likely get the wrong things eaten or dug up, so I’m not prepared to try that brute force approach.

A better approach is to allow the natural predators of aphids time to do their work – these include really tiny parasitic wasps, ladybirds, hover flies, lacewings and small spiders, or even larger predators  such as silvereyes (birds) or very large humans such as myself armed with powerful water sprays.

Luckily for me I know just what attracts silvereyes (Zosterops lateralis) to the garden, especially on hot days like this one; I’ll turn on the sprinkler in the vicinity of the damaged cabbages. Silvereyes like nothing better than to take a shower and will appear from nowhere to dash in and out of the spray.

Maybe they’ll get a free feed with their wash?

If not, I’ll just let these cabbages go or rip them out altogether and compost them – aphids and all. Their neighbours are healthy and will probably resist the infestations, making it through to the pickling and cooking department in a few months time.

Seed-Saving – Free Public Lecture

“These lettuces have had it!” says the cook

“Somebody’s asked me to talk about seed-saving” says the gardener “If they fall asleep during the lecture, at least they get free lettuce seed at the end”

“Huh!” says the cook.

Last year some kind folk from one of the local markets asked me to talk about backyard veggie growing. If they take the trouble to track me down and ask me to speak, I make the effort to get along and share what I know. So I did that. It can’t have been too shabby, because they’ve invited me back to give another talk, at

10.30am on Saturday morning 15th March 2014 at the Payneham Community Centre, 374 Payneham Road (corner of Arthur St), Payneham South Australia 5070.

But there’s just this one thing – I can’t seem to bring myself to give the same lecture twice.

So I hunted around for some other theme, and decided to take my seed-saving activities on an outing.

“Huh?” they said, just like the cook. “How about a flyer?”

So I wrote a flyer – here it is:

'Going to seed!' - how backyard farmers preserve the heritage varieties of vegetables ignored by corporate agriculture.

Over 95% of the vegetable varieties that existed over a hundred years ago have disappeared; they simply don't fit the needs of the corporate food chain looking for tough-skinned, long-storage, travel-the-world vegetables being trucked up and down the country from cold room to supermarket to home refrigerator.

Yet these old heritage varieties still exist in the hands of families and old gardeners who have adapted them to local conditions or grown them on over many generations as a family favourite.

Seed savers keep these tasty sweet remnant varieties alive and pleasing the palate of kitchen gardeners the world over.

Andrew will talk about how to get your hands on old open-pollinated heritage vegetable seeds, how to store them and how to grow them on yourself year after year.