Corn grey leaf spot

Leaf spot disease is caused by fungi of the genus Helminthosporium plant disease that occurs in maize.

• 2.1 Life Cycle
• 2.2 Ecology

Damage

Harmful images

H. carbonum: ellipsoidal, 2-25 mm long spots; first paper-like yard with reddish and often concentric zones, later brown to soot- colored.

H. turcicum: Irregular long oval 0.5 to 10 cm long spots; initially watery gray-green, later gray -brown with narrow dark brown border. Interior partly blackish.

H. maydis: elliptic, 2-25 mm long spots; first yellow-brown, later gray-brown with a narrow red-brown border. Necrotic On wilting seedlings strips. Through a variety of racial formation disease severity and symptom development are very different for each variety. Small stains are difficult to distinguish and can also be confused with Phyllosticta or Kabatiella.

Importance

The fungi are common and can lead to loss of assimilation surface. Although Helminthosporiosen were previously only sporadically inbred lines economically destructive to, but it seems to H. carbonum to gain in importance.

Biology

Host plant: corn

Life cycle

The fungi can be introduced with the seed, but to hibernate with mycelium and spores on straw residues. In spring, the spores usually enter first with rain splashes on lower leaves. Starting from this first patch, done windbürtige infections by conidia.

Ecology

An increased incidence is favored by prolonged periods, as well as by strong thunderstorm sultry rust, which allows double infections. The existence of different races complicates forecasts.

Combat

• Indirect: crop rotation and plowing under of crop residues can reduce an early infestation. The choice of varieties needs to be given increased attention.
• Direct: Seed dressing brings only partial success.