Leaf spot

Leaf spot (Alternaria alternata) is a fungus which causes the appearance of round blemishes found on the leaves of many species of plants, mostly caused by parasitic fungi or bacteria.

Symptoms
A typical spot is "zonal", meaning it has a definite edge and often has a darker border. When lots of spots are present, they can grow together and become a blight or a blotch. Fungal spots are usually round or free-form in shape.

Chemical
Treat with thiram or iprodione. Destroy diseased crops after harvest.

Prevention
Avoid using overhead watering systems.

Chemical
Iprodione, difenoconazole, tebuconazole and strobilurin are suitable protectants.