Wet weather woes
Months of high rainfall and grey days will take its toll on your garden plants and soils. What are some of the common issues facing gardeners during and after these events?
Afew days ago, a brief respite during this month’s rainy days allowed me to wander the soggy, leaf-strewn pathways of my ornamental and productive gardens to see what had become of my patch after over a week of very wet, grey days.
The inability to get into the garden was at times extremely frustrating as, I imagine, it would have been for most gardeners in our region and much of our “Sunshine State”.
What I found wasn’t particularly pretty, but it wasn’t disastrous either.
Periods of waterlogging and wet foliage takes its toll on many plants, with others simply shrugging off the autumn sogginess and either getting on with things, or happily entering dormancy.
With this in mind, it’s a great time to look at some of the challenges these weather events present to gardeners and maybe some ways to reduce the effects of these events.
Fungal attacks will be the greatest challenge for gardeners during and after prolonged periods of wet weather.
Rose growers should be carefully checking the leaves and blooms of their favourite specimens for a range of fungal problems.
Mildews love cool weather and high humidity.
Both powdery mildew and downy mildew will be rampant around now.
Powdery mildew appears as white or silvery powder-like growths on the upper leaf surfaces.
It’ll hit new growth particularly hard, causing curling and distortion, with severe infections causing stunting of the rose bush.
Downy mildew is arguably worse than its powdery cousin, striking quickly when temperatures are around 18°C and humidity above 85%.
First signs are angular spots with a reddish-black colouring, followed by rapid leaf drop from the top of the bush downwards (incidentally, black spot starts at the bottom of the bush and moves upwards).
In the current conditions, organic controls will have limited effect, so it may be necessary to reach for stronger products.
For powdery mildew, triforine, wettable sulphur or mancozeb with sulphur are your best options for control.
For downy mildew, phosphorous acid works well.
Many other plants may be affected by these two mildews, including vegetables and fruits.
Make sure the products you are using are registered for use on those particular plants and observe withholding periods on edible crops.
Another wet-weather problem is that of munching molluscs, namely snails and slugs.
They absolutely love spring and autumn and the current conditions, with many gardeners reporting a huge increase in numbers this year.
Both come out at night to feed, rasping away at foliage on ornamentals and vegies alike.
Being active at night, they’re hard to spot during the day.
Look under items where they may be sheltering.
There are many snail baits on the market but be careful if you have pets.
Look for the baits that only contain EDTA or elemental iron as these are safest around pets.
There are traps that can be half-filled with beer to attract these slimy critters as well.
Another solution may be a specialised copper spray that lasts for months, usually sprayed on soil, pots, tree trunks, but not on leaves.
Saturated soil can present problems for plants that bear ripened fruit.
My oranges and tomatoes were casualties of the last two rain events, both suffering splitting fruit.
This usually occurs when the plant takes up water from a saturated soil and the flesh of the fruit expands, but the skin doesn’t. It’s common in both citrus and tomatoes and may occur in pome and stone fruits as well.
One way to reduce splitting is to maintain consistent moisture during fruit formation.
While it’s hard to deal with excessive rainfall, it’s easier to keep soil moisture at good levels in drier periods through regular irrigation practices.
Mounding your garden beds may help deal with excessive rainfall as this will improve drainage during these events. Soil compaction is another common problem which may occur after heavy or prolonged rain. Unmulched soils will be compacted on the surface due to the impact of raindrops destroying the structure in the top few centimetres.
This then reduces the ability of the soil to accept further rainfall (infiltration) and increases run-off and erosion. Obviously the best way to reduce this problem is to mulch garden beds to a depth of no more than 75mm with a chunky material such as wood chips or bark nuggets. By far the worst problem with soggy soils is compaction from human traffic and machinery.
Make sure that foot traffic on wet soils is kept to a minimum until the soil dries. And even supposedly benign practices such as mowing on a wet soil can cause compaction and the inevitable “wheel rut” pattern seen on some manicured lawns. Finally, prolonged rain events can remove large quantities of nutrients from your soil through leaching.
For your vegie garden and evergreen ornamental beds, it’s a great time to renew lost nutrients with a quality compost or long-lasting organic fertiliser.