Ask an expert

YOUR GARDENING QUESTIONS THIS MONTH

Q SPOTTY SPUDS

Last year my potato crop was disappointing. There were crusty brown marks on the skin. Can I prevent this happening again? JANINE FRANKS, AUCKLAND

A

Your potatoes had a bacterial infection called potato scab. It’s quite common especially in light soils that dry out easily or where soil pH is alkaline.

The scabs are mostly on the surface and the rest of the flesh can be eaten but it is unsightly and the crop won’t store as well as unaffected potatoes.

The disease can be transferred by infected seed potatoes and stays in the soil where an infected crop has been. Don’t be tempted to grow potatoes from the last crop. Instead be sure to purchase new certified disease-free seed.

Choose a new planting bed too. Potatoes should not be grown in the same place for at least three years. Don’t add lime which increases soil alkalinity.

Instead add well-rotted compost which improves water retention. Avoid fresh animal manures which can be too strong and also cause skin blemishes.

Once your next crop of spuds have been harvested, plant a green crop to replenish soil and avoid the build up of pests and diseases.

Chitting seed potatoes (leaving them in a warm place until well sprouted) before planting is also helpful as it reduces the time plants are in the ground before harvest so they are less exposed to potential pests or pathogens. Barbara Smith

Q TROPICAL BLOOMS

I’ve grown two frangipani plants from seed. They are three years old but there are no flowers. Can you shed some light on this? MARIE HARRIS, AUCKLAND

AIt can take many years for a frangipani seedling to flower and the flowers are not the same as the mother plant.

Growing from cuttings is easy and, with the right conditions, the new plant could flower the following season.

Frangipani require well-drained soil and lots of sunshine. Keep in a warm, frost-free position over winter but do not water while dormant. In spring, when the first leaves sprout start regular watering and fertilising.

Cuttings and plants can be purchased from frangipani-flowersplants.co.nz. See facebook.com/ frangipanihut for growing tips. Caro Leuschke, The Frangipani Hut

Q SICKLY LILAC

The bush still flowers and survives but the leaves are spotty. Any ideas? I have made sure it is watered and fed. JENNY TROTTER, CHRISTCHURCH

ASpots may be due to physical damage, for example hail, but this looks like leaf spot caused by fungal infection. If there are also twigs showing signs of dieback, it’s bacterial blight. Either way, the treatment is the same.

Spray with Yates Fungus Fighter plus Grosafe Enspray 99. Or for organic control, Grosafe Free Flo Copper plus Grosafe Enspray 99.

Avoid overhead watering which splashes the fungal spores around. Prune to increase air movement through the plant and reduce crowding by other shrubs. You may have to sacrifice some of next season’s blooms to improve its overall health. Barbara Smith

Q POISON POPPIES?

Thank you for the poppy seeds in the April issue. My young Labrador is prone to eating plants. Are poppies toxic to dogs? MILLY COTTRELL, CHRISTCHURCH

APoppies, along with hundreds of other plants, can be poisonous to dogs. So many everyday plants from tomatoes to daffodils and even Christmas trees are potentially toxic, it is impossible to eradicate them all from your puppy’s surroundings. Familiarise yourself with possible toxins (avocados, peach leaves, beans… the list goes on and on). Learn to recognise poisoning symptoms. Create a safe space for the puppy to be left alone and supervise at other times. Lock away garden and other household chemicals. Keep rubbish bags and compost out of reach. There’s more information at justdogs.co.nz. Barbara Smith