This week I have had two readers asking about damage that’s happening to a hibiscus and a citrus tree.
In both cases the leaves were being eaten but when examined there are no culprits found.
In most cases when you can not find a caterpillar or any other leaf eating pest then it is likely to be either beetles or birds but in these two damaged plants it would be beetles as birds do not like the taste of hibiscus or citrus foliage.
Now that the weather is settling and temperatures rising we will see a lot of damage caused by either grass grub beetles or black beetles as they hatch out and start a new life cycle.
These beetles come out at dusk to feed, mate and lay eggs during their 6 odd weeks as an adult.
Gardeners living near paddocks or playing fields may be shocked as the sun goes down and swarms of hundreds of beetles fly into their gardens to do a lot of damage to several plants include the fore-mentioned plus roses and beans.
If you have plants with holes in them and no sign of the culprits then go out just after dark with a torch and check the plants.
If there are beetles feeding then mix up Wallys Super Neem Tree Oil at 5 ml per litre of water and add to that half a mil of Wallys Super Pyrethrum and 1 mil of Raingard.
Spray the beetles directly that are on the foliage; the pyrethrum is a quick knock down affecting the nervous system of the pests causing a quick death.
The Super Neem Oil has the anti feeding properties which will stop the pests feeding so that damage is reduced and they will die of starvation after a few days.
The pyrethrum is deactivated by a couple of hours of sunlight the following day, the Super Neem Oil will last on the foliage for 7 to 10 days with increased protection from the Raingard.
If you are unfortunate to have vast numbers of beetles then it would be best to repeat every night for a while.
If only a smaller number is seen than keep and eye on damage each day and repeat at night when you feel it would help control new hatchling’s.
At the beginning of the season all the insect pests will start to emerge from their winter dormancy and begin to build up their populations.
With some this can be a very quick process starting with a few and within a month having increased by 200 to 500% ( 10 x300=3000x 300=900,000) that is a two to three months period and disaster for the pest’s host plants.
Knock out those early starters and your insect pest problems will be minimal in the January, February period unless they are invading from untreated gardens nearby or next door.
One of the first lines of defense is to use several Sticky White Fly Traps which can be hung off stakes outdoors or from the roof in glasshouses.
Ideally the trap should be just above the growing plants and raised as the plants get taller. The traps are 250mm x 100mm with a special sticky substance that stays sticky all season catching whitefly adults, psyllids, aphid adults plus other insects.
It is amazing how many insects are caught so quickly.
The next line of defense is Wallys Neem Tree Granules or Powder which is applied to the soil or growing medium in the root zone.
The granules which are called Neem Cake in India are the residue of the Neem Tree seeds which were cold pressed once to remove Neem Oil. This leaves a very dark granule with a very Neem smell.
If the Neem Granules are a light golden colour it means that they have had several extractions of the dark oil causing the much lighter colour.
It is the very dark granules/powder you want as they still have lots of oil still.
When applied to the soil surface and with rain or watering the oil leeches out into the soil and is taken up by the plant’s roots.
Any insect pest feeding on the roots gets a dose of Neem and stops eating forever. This is great way to control soil insects such as root mealy bugs, nematodes, grass grubs etc.
The plant takes the Neem oil up into itself and then discovers it is not something it needs so starts converting it to carbohydrates.
If the plant is quick to do this then there is very little effect on any insects feeding on the foliage. (Examples I have found is cucumbers and beans).
If the plant is slow then the Neem gets through to all the foliage on the plant and any insect feeding on the plant will get a dose and stop eating forever.
(Examples that work is tomatoes, potatoes, brassicas, citrus and rhododendrons).
The great aspect of this is removing the need to spray while at the same time not harming beneficial insects such as ladybirds and bees.
Another aspect of the Neem Granules is the smell which is fairly strong and can confuse some insect pests as they can not smell their host plants.
For those plants that need further protection to control pest insects then the New Wallys Super Neem Tree Oil is the answer.
Used only late in the day when the sun is low on the horizon (to prevent burning) and when most insect pests have settled for the night or beginning to emerge if they are nocturnal.
The beauty of Neem oil as opposed to all the chemical sprays it is very safe to use.
It also means that beneficial insects including bees and bumble bees are not harmed by Neem; unlike the dangerous chemicals which can still harm bees months after they have been used.
Spraying under the foliage of plant’s leaves is very important as most insect pests are under the foliage protected from predators and weather.
Using a pump-up sprayer with a wand allows you to easily spray under the foliage of taller plants and on low plants you can fold back the foliage with one hand to spray under the leaves.
After you have finished spraying with Neem Oil always tip out any spray not used onto the soil in the root zone and rinse the sprayer out with clean water.
Use warm water to mix Neem Oil and in cooler weather place container in a jug of hot water to allow it to pour as it goes solid in the cold.
Image credit: Markus Spiske
Products mentioned are from Wallys Range of products and can be found in some garden shops or by Mail Order on www.0800466464.co.nz
Problems ring me at: Phone 0800 466464
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