If your leaves are wet past 8-9am for two or three days running…

If your leaves are wet past 8-9am for two or three days running, that's blight weather, and the spray needs to already be on before you see a spot.

In a wet year it can take 60-100% of an unsprayed crop, and once the lesions show, it's too late to reverse with a spray — only to slow it.

Start with certified, blight-tolerant seed, spaced 75cm between rows and 30cm in the row. Ridge up at the 4-8 leaf stage and again 2-3 weeks later, across the slope rather than down it, so water drains instead of pooling around the plants.

Spray a protectant (mancozeb or chlorothalonil) every 7-10 days from emergence, tightening to 4-5 days in constant wet weather. Once blight turns up nearby, add a systemic tank-mixed with the protectant, every 5-7 days, and stop spraying about 14 days before you dig.

When you harvest, cure the tubers a week or two in shade with airflow. Store what you'll eat or sell in the dark at 6-8C, and keep your seed potato in indirect light instead — it holds short, sturdy sprouts ready for next planting.

Are you seeing any leaf spotting yet this season? Reply and tell us.

https://divisi.africa/insights/growing-irish-potato-wet-year-late-blight-storage-el-nino/