Spraying Potatoes for Blight: A Discussion on Effectiveness and History

As a gardener, it's essential to understand the importance of keeping potato leaves dry to avoid blight without relying on chemical controls. The key to avoiding this disease is to prevent spores from germinating on wet leaf surfaces. However, there is no conclusive evidence to support this method, and considering the widespread nature of wind-borne spores, it may be a waste of organic matter not to compost infected potato haulms and tomato vines.

In horticultural literature, advice often suggests destroying infected potato haulms and tomato vines to limit the spread of blight. While this approach might seem logical, it's crucial to consider the disease's natural dispersal through wind-borne spores that can travel vast distances, even across bodies of water like the Channel and Irish Sea.

My personal experience with growing potatoes in the north east has shown that blight is less prevalent in cooler climates. In fact, during a blistering summer in 1995, I was unable to infect a single plant. Conversely, during drought years, it's challenging to encourage blight to take hold, making it difficult to test varieties for resistance.

I have conducted controlled blight field trials in the past and would like to hear from others about their experiences with differences between places and over time. For instance, have you noticed any changes in blight incidence compared to ten or twenty years ago?

As someone who has grown vegetables in various locations, I've observed that blight can affect outdoor crops in different ways depending on the region and weather conditions. In NW Wales, where I lived for ten years, potatoes were often affected by mid-July, and outdoor tomatoes were difficult to grow. However, when I grew potatoes under cover and planted them as early as possible, with a view to harvesting in early July at the latest, I was able to avoid blight.

It's fascinating to note that, during my childhood in Lancashire in the forties and fifties, blight was rarely mentioned. Even on allotments in Leeds since the sixties, where I grew potatoes and tomatoes, I never suffered from blight myself or saw it affect others' crops. However, I'm aware of the devastating impact of blight during the Irish famine in the nineteenth century.

Assuming that the problem has worsened over the years based on the frequency with which blight is discussed online, it's essential for gardeners to be aware of the disease's history and the various approaches to managing it. By understanding the factors that contribute to blight and adopting effective strategies, we can better protect our crops and maintain healthy gardens.

Spraying potatoes for blight