15.4 C
Tuesday, July 16, 2024

Popular Now

Wally Richards
Wally Richardshttp://www.gardenews.co.nz
Wally Richards has been a gardening columnist for over 30 years. Check his websites - for gardening news and tips visit www.gardenews.co.nz. For mail order products visit www.0800466464.co.nz. Wally also has a gardening problem help line on 0800 466 464.

Gardening with Wally Richards: Powdery Mildew and other diseases

This is the time of the year that the disease called Powdery Mildew will attack a number of plants in your garden.

Powdery mildew is a common fungus that affects a wide variety of plants. It is easily identified and appears as light grey or white powdery spots usually found on infected leaves, but can also be found underneath, or on stems, flowers, fruit or vegetables.

Powdery mildew news

Powdery mildew, mainly caused by the fungus Podosphaera xanthii, infects all cucurbits, including zucchini, squash, cucumbers, gourds, watermelons and pumpkins.

Powdery mildew infections favor humid conditions with temperatures around 20-27° C.

Which recent rains and warm temperatures have been the cause of what we now see in our gardens.

A little early this season as it more often appears with the autumn rains in March and April.

Been early means a problem in obtaining the maturity of some crops such as pumpkins.

Unlike some other diseases, powdery mildew spores do not live in the soil, but rather are transferred from plant to plant by the wind.

If possible, plant cultivars that are resistant to powdery mildew and be sure to rotate crops in your vegetable garden.

I always describe diseases and insect pests as the cleaners of Nature, helping to take out the weak plants and contributing to their demise at the end of the season.

But when a disease such as powdery mildew strikes before the end of the season it means you may not get the best out of infected plants before they fail completely.

Pumpkins, zucchini will stop growing as they cannot gather energy from the sun when their leaves are covered with the powder.

That means their fruit may not mature and thus be wasted.

My easy solution is to spray the affected foliage with Wallys Super Neem Tree Oil; it instantly turns the leaf back to green and allows the plants to carry on for a while longer.

Only spray at the end of the day when the sun is off the plants as oil and sun/UV become a weed killer and you would burn the leaves.

One reader this week from up Auckland way asked about when he could spray his peaches for brown rot as he has been spraying every week the fruit with Wallys Super Neem Oil and Raingard for preventing the guava moth maggots from entering the fruit.

An interesting dilemma as the oil will have an adverse reaction with the sprays needed to control brown rot in stone fruit.

My recipe for brown rot is a combination of Wallys Liquid Copper, potassium permanganate, spray-able sulphur with Raingard added.

If you have brown rot problems then that spray program should be started after the fruit have formed and reached about half their full size.

No need to spray the tree just the fruit to protect them as they head to maturity.

Spray two-weekly till harvest.

One gardener that reported back to me about 2 years ago said that he was able to obtain about 90% of his crop from using the program.

He also thought that because he missed one 2 weekly spray in the middle because he had to go away otherwise it may have been 100% successful.

The previous season all his fruit was lost which is a good indication how successful the combined sprays are.

Another disease that could be appearing on the trunks of your tomato plants at this time is a fungus growth grayish in colour that is going to kill your plants.

The cause of the disease is the insect pest, tomato/potato psyllid.

The nymphs when feeding on the foliage inject a toxin into the plant which will cause the fruit to be smaller, the leaves to turn yellow and drop and the death of the plants.

There is only one solution that is 100% effective for all plants which are hosts to the psyllid and that is Wallys Cell Strengthening spray/drench program.

Three components – Wallys Silicon and Boron soil drench which is applied prior to or at planting time and again two weeks later.

By the way some gardeners have told me that they have use the drench on other plants which has resulted in very healthy strong plants.

This is likely due to the boron aspect as well as the silicon and boron deficient soils will prevent some plants from preforming as well as they could.

Avocados and cauliflowers are two that come to mind.

There is on our mail order website a natural slow release boron you can use in your gardens every couple of years or so.

The Cell Strengthening spray with the Super Spreader that drives the former into the plant should be applied weekly while the plants are growing.

If your tomatoes are failing and you can get some Russian Red seedlings plant them out with the strengthening products as it is not too late to get them going for some late cropping.

Feed them with Wallys Secret Tomato food with Neem granules and add the Magic Botanic Liquid to the Cell Strengthening sprays.

Happy Gardening.


The organic swell of New Zealanders that are protesting against Mandates and loss of freedoms is growing not diminishing.

The Government and the media have desperately being trying to paint the protesters in a bad light which is not working as people that have been to Wellington or Picton have seen, peaceful, happy, sharing people there with a cause.

A few fringe elements which have been quickly controlled.

The childish acts of Trevor Mallard have been condemned and the cowardice of politicians to hear what so many protesting New Zealanders want can be described as pathetic.

Head of Police wants negations to resolve the protests but not our Government who would have to admit they made mistakes and were wrong.

On a more serious note studies from overseas are frightening as to what long term affects are happening.

Remember the quotes ‘I am the one source of truth’ and ‘Safe and Effective.’

The new fear is that omicron is out of control spreading fast, ‘Be afraid, very afraid’

But the opposite is the truth.

Less potent than seasonal flu. I bet every one will get a dose just like the flu every year when it goes around and get over it as normal.

It could be though from very recent studies that vaccinated will be worse off than unvaccinated. Time will tell if that is correct.

So do the obvious get vitamins D and C in to your body, eat healthy food out of your garden and lay off the booze and smokes.

Problems ring me at: 0800 466464
Email: wallyjr@gardenews.co.nz
Web site: www.gardenews.co.nz

Promoted Content

No login required to comment. Name, email and web site fields are optional. Please keep comments respectful, civil and constructive. Moderation times can vary from a few minutes to a few hours. Comments may also be scanned periodically by Artificial Intelligence to eliminate trolls and spam.


Please enter your comment!
Please enter your name here




Daily Life


overcast clouds
12.1 ° C
12.3 °
11.7 °
92 %
100 %
13 °
13 °
13 °
14 °
11 °