South Australia - 24th March 2003

Same reader questioned why I recommended the removal of the purple-brown floating Azolla from water features. It does reproduce rapidly and tends to reduce the penetration of light into the pond water, causing algal blooms and poor plant growth of other water plants. I’ve had ponds with it that always got murky and I’ve got one now without it and it never gets murky, so what more can I saw?

There’s a lot of “Stone fruit shot hole” around this year on Apricots principally, although I believe it can occur on Nectarines and Peaches, but I must admit, I’ve never seen it on them. You know you have it by the small holes all over the leaf surface, which causes a drop in productivity. It is one of the few bacterial diseases in our gardens and it’s one reason that the use of some fungicides on it for control, does not remedy the problem.

You can however control “Stone fruit shot hole” with a spray of copper oxychloride and 30 ml per litre of PestOil in autumn and again after total leaf-fall in early winter, with another spray as first flowers open in spring. This is not a remedy for “Peach Leaf curl”, for that you need to spray Kocide with 30ml per litre of PestOil at full dormancy in mid winter and again just as buds swell, but before bud burst.

Whitefly infestations are everywhere at present. You can get a short-term control by a spray of Confidor but Tomatoes have to be left unpicked for 3 full days and other crops for longer periods according to the label. The yellow sticky traps work a treat, but I’m going through them at a great rate, whoever I can pick my vegies every day and they get a lot of European Wasps too. If sourcing them is a problem, I have them from my website www.greenfingers.com.au posted anywhere for $9.50 a pack of 5.

The Tomato Russet Mite is the culprit that has caused your tomato vine leaves to turn a rusty brown. Control can only be gained by using tomato dusts at the early stage of growth. I stop using the dusts as soon as fruit appears and that gives me about 3 months of mite free vines, but they always catch up and no varieties are resistant! The spray that you can resort to for all summer control is Folimat 50, which is a systemic and knockdown, but has a 7 day withholding period on vegetables and herbs. The choice is yours.

There is a lot of late development of this year and those that develop tendrils (pumpkins & melons), need to have their tips removed to induce the flowers to set. Harvest pumpkins only when the handle of the fruit turns brown, then stack them on a sheet of iron or a corrugated roof of a shed maybe. That is necessary so they don’t rot and they also need to after-ripen, unlike most vegies.

“My Apricot and Almond trees have gummosis, because gum is oozing from their trunks, so what to do?” I hear this a lot, but gummosis does not automatically mean your trees are affected with Eutypa, which is the proper name for gummosis or dead arm as it is called when it affects vines. It’s the almost instant death in mid summer of a single branch that signals the presence of Eutypa.

Remove the dead limb by all means, as far down the stem as is practicable, but there is little else that can be done. There are no miracle mastic sealants, solutions or sprays that will halt the inevitable. No amount of dipping secateurs into disinfectant at pruning time, but the tree may survive another 5-10 years, with a limb lost every year or two, so enjoy it while you can. There are no resistant rootstocks nor is there a reliable treatment for control available to home gardeners, so start planning a replacement.

There are some magnificent Walnut trees on the hills, but always located on the sunny aspect on a sloping site, where they get morning sunlight. Your best way to protect you tree is to keep the weed or grass competition under the canopy under control. Spray knockdown herbicide or keep mowed low, as the humidity causes fungal diseases that affect nut set. Young trees need a top-dressing of a handful of superphosphate at their root zone in each of their first three years to develop a good root run.

I witness the odd Ficus benjamina that having lived its useful life as an indoor plant, is given a reprieve out in the garden and the owners are quite happy for a few years as this hardy subject adapts to life in the big out doors. But wait a minute.

Take a detour past the Hyde Park Tavern some day and on the Mitchell Street entrance there is a Ficus benjamina that must be eight metres in girth and lifting all around it. Lovely tree in a parkland setting, but near your house… no way. Its root run is two and a half times its height. That’s 45 metres, so if your yard is really large go ahead and plant one, but the compost heap may be the best place to relocate that indoor plant!

Whitefly infestations are common on cucurbits, tomatoes and carrots and of course Ash trees at present. The little sapsuckers deplete the vigour of your plants and greatly reduce crop set and in the case of Ash trees cause a premature leaf fall. You can get a short-term control by a spray of Confidor (at least on vegies) but Tomatoes have to be left unpicked for 3 full days and other crops for longer periods according to the label.

The yellow sticky traps work a treat, but I’m going through them at a great rate, however I can pick my vegies every day and they catch a lot of European Wasps but not bees. If sourcing them is a problem, I have them from my website www.greenfingers.com.au posted anywhere for $9.50 a pack of 5.

Lisianthus success stories, from folk who picked them up at the Adelaide Royal Show or ABC Car Park Capers recently are pouring in and it seems that the conventional wisdom for growing these bedding plants is that they need a full sun aspect, good drainage, without any root competition and best on light soils, with fortnightly water soluble fertilizer. They thrive in pots that are at least 20cm (8”) deep. Available in punnets right now and up to late spring.