As a fruit grower, lying in bed listening to rain on the roof can bring up a wide range of emotions, both good and bad. In our typical dry summers most people welcome rain when it comes, so it never seems appropriate for us to express concern about the damage it can do to fruit. However, it hasn’t rained for a while, so this week we reflect on the question – “Is rain good for fruit?”
Like everything in farming, the answer is complicated, and depends on lots of different variables, so let’s break it down a bit.
1. Trees like rain better than irrigation water — up to a point! As a gardener, you’ve probably noticed how “perky” your garden looks just after rain. One of the reasons (apart from the leaves being cleaner) is because the rain carries dissolved nitrogen which is easily absorbed by the plants, giving them a nutritional boost. Too much rain, however, and the soil can become waterlogged, creating anaerobic conditions, which actually stops the plants’ roots being able to take up nitrogen! The other advantages of trees receiving their water from rainfall (rather than irrigation) are that the entire root system gets water (rather than just at the point of water delivery), and if you’ve been keeping your garden on rations due to dry conditions, they just love the opportunity to get their fill of water for a change!
2. Rain can trigger fungal disease. One of the biggest pest and disease risks in an organic farm (or garden) is fungal disease, and nearly all fungal diseases are triggered by wet conditions (at the right temperature). In general terms, the more rain, the more fungal disease. This risk is highest at the beginning of the season (i.e., at flowering time in spring), and then gradually decreases as the season progresses. During autumn, if the summer has been generally dry and there is not much fungal disease around, the risk of a new fungal outbreak is relatively low.
3. Rain can cause physical damage to fruit. This is very specific to the type (and even variety) of fruit. For example cherries are particularly vulnerable to splitting from the rain, and some varieties of apricots also split easily. Hardier fruit like apples and pears, however, rarely experience physical damage from rain.
4. “Hard” rain can damage all fruit. Storms that bring rain often also bring hail, and that can be completely devastating to all fruit. Hailstorms are very random and localised, so it”s pretty much the luck of the draw with this one, though if you live in a hail-prone area, netting can definitely be your saviour. All fruit are vulnerable to hail damage, including apples, pears, plums and quinces.
5. Rain is good for the landscape. When you’re trying to grow food in an arid landscape (as we are), the general impact of rain (as long as there’s not too much, or too quickly) is generally FABULOUS! It fills water storages, keeps the bush alive, helps to sustain our farming communities, and helps backyard fruit growers maintain their own food security. We love it….except…. when there’s too much! If rain becomes flooding and the soil becomes saturated for too long, it can lead to ALL sorts of problems! Anaerobic soil conditions, trees dying, waterborne soil disease, nutrient leaching, dams breaking their banks, and the list goes on. We’ve seen it before when the drought broke in 2010/11.
6. Rain is good for mental health. It’s a generalisation, of course, but very often rain can be a huge relief to farmers and others in the community, especially if it is relieving the pressures of trying to farm in a dry landscape, though as you can probably see from our list, it totally depends on the amount of rain, and the context!
Regardless of the timing of rain within the fruit season, it’s important to make sure your soil can act as a big “water storage tank” when it rains. As well as building really healthy soil (which is good for both water storage and drainage in your soil), techniques like swales and keyline (covered in this short course) can make a huge difference to how well your soil will store rainfall.