Protecting season’s new potatoes
Now is a good time to buy new season seed potatoes and sprout them for planting out.
While planting out is mostly governed by frosts and the damage they can do to an early crop, there is an even bigger danger.
The potato psyllid in some areas has caused total crop loss.
An early crop of fairly quick maturing potatoes will suffer only minor damage in most gardens.
Later in the season when pest numbers build, there is a noticeable increase in damage and crop failure.
Potato crops planted in November or December will need a lot of protection to produce good spuds for storage.
In the worst affected areas of New Zealand, October plantings will also need plenty of protection.
The following information is taken fromMAF New Zealand’s web page:
‘‘The adult tomato/potato psyllid is about the size of an adult aphid but looks like a tiny cicada under magnification.
‘‘The female lays yellow eggs that are attached by stalks to plant leaves, usually to the leaf edges.
‘‘Psyllid nymphs hatch from these eggs and after five moults, become adults.
‘‘The nymphs are flat scale-like insects which are mostly inactive but move when disturbed.
‘‘Later in the season when pest numbers build, there is a noticeable increase in damage and crop failure.’’
‘‘Nymphs and adults feed by sucking plant juices, which is how they are thought to spread a substance called liberibacter - the toxin that does the damage.
‘‘Nymphs and adults secrete plant sap as white granules called ‘psyllid sugars’ visible on the leaves.
‘‘On tomatoes, symptoms of psyllid yellows disease are the yellowing and stunting of the growing tip and a cupping or curling of the leaves.
‘‘Many flowers may fall off the trusses of infected plants and fruit may be small and mis-shaped.
‘‘On potatoes, psyllid yellows causes a stunting and yellowing of the growing tip, and the edges of the curled leaves often have a pink blush.
‘‘The stem may have swollen nodes and show a browning of the vascular tissue.
‘‘After a while, infected potatoes develop a scorched appearance and plants collapse prematurely.
‘‘Potato plants that are infected at an early stage develop numerous small tubers.
‘‘Other host plants of the tomato/potato psyllid include apple of peru, capsicum, chilli, egg plant, kumara, poroporo, tamarillo, pepino and thornapple.’’
‘Psyllid yellows’ in tomatoes and potatoes, and ‘zebra chip’ symptoms in potato tubers can drastically reduce crop quality and yield.
The problem is greater than just protecting tomatoes and potatoes. Other plants and weeds, common convolvulus for instance, also host the pests, which means they can re-infest your crops.
If you leave any mature potatoes in the ground, cut the tops off and cover the stubble.
To ensure a decent crop of spuds, home gardeners need to adopt comprehensive pysllid protection strategies.