I am having fungus problems with my tamarillos. I have sprayed religiously with Yates Nature's Way, to no avail. What else should I do?
- Diana

My pick is that it's not a fungal problem. The North America potato psyllid is currently infesting New Zealand gardens. Your tamarillo or solanum betaceum is part of the solanaceae family, the same as the potato which has devastated many tamarillo trees nationwide, including mine. The psyllid sucks on the leaves and shoots of the tamarillo, spreading the bacteria, liberibacter. You need to stop the psyllid, which looks a bit like a small cicada. Hang a trap in your tamarillo made of yellow plastic covered in petroleum jelly (or wrap a yellow Kings potting mix bag around a strip of cardboard). Spray under the leaves with oil-based sprays, or remove the eggs with your fingers. For a chemical solution you could use Yates Supershield. Maintain a spray programme every 10 to 12 days as this timeframe will disrupt the life-cycle of the psyllid. You may have to work harder for your fruit but they'll taste better when you get them.

I want to plant a lemon tree, but I don't want a Meyer lemon. What varieties can I get that are similar to lemons that grow in France, Spain and Italy?
- Patti Martin

The main lemon variety grown in the Mediterranean is the Verna which likes an arid hot climate and is a heavy late cropper. Verna was introduced successfully into South Australia in the 1990s so may be available in New Zealand if you hunt around. Other varieties more common in New Zealand that are not a Meyer and have less seed and a thin skin are the beautiful Eureka, which crops all year, and the Lisbon, which is better in cooler regions. Both are similar to the Verna.

You mention sowing beneficial insect blends. Could you elaborate on these please. Does any seed company have a mixed seed packet for this purpose? If they don't - hint hint!
- Dean Brown

Kings Seeds does a beneficial insect blend which includes the following: buckwheat, dill, bishop's flower, parsnip, ammi visnaga, fennel, daucus carota, phacelia, bergamot and alyssum.

This kind of mix is a really effective way to get the good bugs into your garden.

Re: your garlic and baking soda spray - my lime and lemon trees are starting to be hit with aphids and thrips. I'm looking for an organic or natural solution, will this help the citrus as well?
- Victoria Blake

I use it all the time on my citrus. If you have a bad infestation of white fly you need to spray at least once a week. Make sure you spray under the leaves and try to up the oil content as much as possible. At some point though it won't dilute in the sprayer, so either add more soap or reduce the oil a bit.

Ask Justin a questionemail gardening@nzherald.co.nz

- NZ Herald