By Penny Woodward

Heirloom French pumpkin Potimarron

Pumpkins, zucchini, marrows and cucumbers need bees to pollinate their flowers before the fuit will set and start to grow. These plants all have male and female flowers and the bees need to fly into the male flowers, collect the pollen while feeding on nectar and then carry the pollen to the female flower. If this doesn’t happen then the little pumpkin (or zucchini or cucumber or marrow) that has started forming at the base of the female flower, will yellow and fall off. In very hot weather you may only get male flowers. This will mean that no pumpkins form during this time. There’s not much you can do about prolonged hot weather, except to plant at a cooler time of year, but if your pumpkins are not forming because of a lack of bees then then there is an easy solution. Take things into your own hands (literally) and do the pollinating. Look at the pictures to see how to tell the male and female flowers apart and then pick a male flower. Break off the petals so that the central stamens are exposed, these are covered in pollen. Poke this into the female flower so that the stamen touches the central stigma and the pollen is transferred. One male flower can be used to pollinate several female flowers. If you don’t want to break off a male flower, then use a paint brush to collect pollen from the stames in the male flower, and then transfer this pollen by touching the brush onto the stigma in the female flower. Easy. Pollination is best done in the morning as the female flowers close up in the afternoon.

Female flower with the small pumpkin forming at the base

Typical long-stemmed male flower

Break off the petals of the male flower to expose the stamens

A cornucopia of produce

I’ve had a cornucopia of cucurbits this year, with lots of ‘Black Beauty’ zucchini and and bright yellow button squash. The pumpkins are not producing as prolifically because I planted them in an out of the way position with not enough sun, but the plants are still growing and the pumpkins are getting bigger. Unfortunately, for the last few weeks the powdery mildew has also been growing. Powdery mildew is a fungus that attacks cucurbits (zucchini, marrow, pumpkin, cucumber etc) and grapevines, some fruit trees and a range of other plants including begonias and roses. It first appears as pale grey spots on the surface of leaves, spreading to cover the whole leaf and stem. If untreated, eventually the whole plant will shrivel, brown and die. Powdery mildew is most prevalent in moderately dry regions, when the weather starts to cool in autumn and where water sits on foliage for long periods. Almost counterintuitively, it is less likely to be a problem in wet weather as well as very hot, dry weather.

This yellow and black ladybird dines exclusively on powdery mildew

Yellow button squash bear prolifically but are quite susceptible to fungal infections

The first sign I had of it’s presence a couple of weeks ago were the delightful small yellow and black ladybird Illeis galbula. These cute bugs feed exclusively on powdery mildew (such an unexciting diet, imagine spending your whole life eating nothing but powdery mildew!). Its almost worth having this fungal problem just so these ladybirds can find a home and food in your garden. As soon as I realised that powdery mildew was around, I carefully cut out affected leaves and stems, and instead of putting them into the bin (which is what you should do to stop it spreading), I put them into a remote corner well away from anything else that could be affected. This meant that the ladybirds could keep feeding and build up their populations and so come back to the plants when they became reinfected. One thing I have learnt is that in our climate at this time of year, you can never completely rid your garden of powdery mildew. But you can slow it down and get a few more weeks harvest from your plants.

Once you’ve removed the obviously affected leaves, spray the rest of the plant with nettle or milk spray. I start with milk and alternate with nettle. See the recipes below. Always spray in the morning or you might exacerbate the problem. Otherwise, don’t water the leaves especially in the evening and thin them out so they are not so crowded.

Leaves completely covered in powdery mildew

Other sprays that have been used to control powdery mildew are allocasuarina, bicarbonate of soda, chamomile, chives, elder, garlic chives, hyssop, mustards and white cedar.

Milk spray
In the 1990s Wagner Bettiol of the Brazillian Agricultural Research Corporation noticed that byproducts from milk processing factories killed powdery mildew on zucchini crops. His subsequent experiments showed that it was not only as effective as registered commercial fungicides but that it also acted as foliar fertilizer and boosted the plants immune system. In Australia milk spray has been trialled on crops like wine grapes in several Australian states.  It has been found to be as effective against powdery mildew as non-organic fungicides on some grape varieties in most conditions. Other trials have also shown that there is negligible difference between full cream, skinny and even powdered milk.

Water cucumber plants with nettle spray to lessen the risk of downy mildew

Recipe Combine I part milk (preferably organic) with 9 parts water and use immediately. Spray the entire leaf, top and underneath, once a week. Spraying is more effective if plants are not grown too closely together and if the spray is used as soon as the problem occurs.

Nettle spray
The perennial stinging nettle Urtica dioica grows from a spreading rootstock to 1m in height in good conditions. The opposite leaves are dark green, crinkled and toothed and have a pointed tip. The whole plant is downy in appearance and covered with stinging spines, which can be very painful when brushed against. An antidote for a nettle sting is the juice of the nettle itself but dock, rosemary, mint or sage leaves rubbed on the wound will also relieve the sting. Nettle spray acts as a mild fungicide and general tonic, making plants more resistant to diseases and pests. It is sprayed on leaves or watered around plants to prevent fungal attack, especially powdery mildew.

Recipe Cover a firmly packed cupful of chopped nettles with 1L of water. Bring to the boil and simmer for 10 minutes. Cool, strain and use within a few days.

Rising costs have combined with anxiety about food security to create a critical moment for people considering growing their own food. Right on cue is “Vegies A-Z”. It’s the third OG special (after Getting Started, $10.00, and Fruit, $10.00). Vegies A-Z combines new material with recent OG articles from reliable writers. My quibble with this third volume is that there is not more on soil preparation, which is crucial. Perhaps that’s in Getting Started? Perhaps the three volumes need to be read seriatum, and would make a great gift, possibly to yourself. PW is a major contributor. — AMS.
Note: There is more on soil preparation in Getting Started which is unfortunately currently out of print. A reprint is planned for later this year
Borrow a copy from your library, buy one from your local newsagent or go to the store on this website and buy a copy online