Digging the Dirt: Be alert to perils of the pesky potato psyllid

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The beginning of May was very much like a return to summer. Even blackbirds seemed confused enough about the temperatures to begin their territorial singing, in preparation for nesting.
Now the month has moved on, temperatures have come more in line with seasonal expectations.
While there have been a few showers, moisture levels in the soil remain below what would be considered ideal.
The touch of frost on one or two mornings has been enough to finish off pumpkin vines and outdoor tomatoes.
Yams have also been hit, although there is enough remaining leaf to keep filling tubers for now.
The winter vegetables planted through February and March have survived the autumn white butterfly onslaught and are now thriving in the cooler temperatures.
A boost with a liquid fertiliser solution will help keep growth going while temperatures cool.
There is still time to plant green manure crops in any unused parts of the garden.
This will keep the area covered, preventing weeds and provide some in situ compost when dug in before spring planting.
Broad beans can be sown or planted from now. The varieties exhibition long pod, a tall heavy cropper, Evergreen, which is a midsize plant with tasty green beans, instead of the usual tan colour, and Janet, an early, shorter-growing plant that doesn’t require staking.
Just dig in some well-rotted compost and a handful of fertiliser at sowing and this will be enough to feed them until spring.
In the orchard, the fruit crop is pretty much finished for the season, with just a few golden delicious and Fuji apples still on the trees.
Any windfall fruit should be buried or binned, along with fallen leaves, toreduce disease and pest carryover for next season.
The winter pruning can also be undertaken from now. Dry sunny days are best, allowing time for any wounds to heal before infections can invade damp surfaces.
It’s best to seal any larger cuts with pruning paste.
It’s almost time to be thinking about sprouting early potatoes for next season.
It seems, looking forward, Timaru gardeners need to be mindful of the new pest in town, the potato psyllid.
In previous seasons damage was sporadic, however, this season, the damage has been severe in some peoples gardens, my own included.
The symptoms include ill thrift in plants, a yellowing (sometimes also purple colouring) of young growth. If the plant is hit early by the pest, the crop consists of marble-size tubers.
When the crop is hit at a later stage, the tubers are discoloured and watery when cooked.
One of the problems with this pest is its tiny size. It looks like any one of many insignificant flying insects that inhabit our gardens, about sandfly size.
It is the feeding of juveniles, barely visible to the naked eye, that causes the damage.
Like mosquitoes carry viruses, these little beggars carry a bacterium that when injected into the plant during feeding, stunts growth completely.
What measures can be taken to control this pest? If possible, plant early and use fast-maturing varieties.
While commercial growers have an armoury of insecticdes at their disposal, home gardeners’ options are restricted to Mavric or Confidor. Another option may be using insect barrier nets.
Once a reliable crop in the garden, potatoes now require careful management to produce.
The thing that is always left out of the hype about trade deals and globalisation is the parallel globalisation of pests and diseases, making growing food for ourselves a more difficult prospect.
Keith Omelvena is an avid gardener and the owner of Greenleaf Plant Centre in Timaru.