What causes yellow spots on corn leaves?

Yellowing corn leaves are most probably an indicator that the crop is deficient in some nutrient, usually nitrogen. Corn is a grass and grass thrives on nitrogen. The plant moves nitrogen up the stalk so a nitrogen deficiency manifests itself as corn leaves turning yellow at the base of the plant.

What causes brown spots on corn leaves?

Northern corn leaf spot is caused by a fungus called Bipolaris zeicola (syn. Helminthosporium carbonum). It overwinters on corn residue. There are several races of this pathogen that can be found in the Corn Belt, but races 2 and 3 appear to be the most common.

What is leaf blight disease?

Leaf blight disease is caused by the fungus Helminthosporium turcicum Pass. The disease develops on sorghum leaves particularly under humid conditions by producing reddish-purple or tan spots that coalesce to form large lesions. It attacks seedlings as well as older plants.

What is Helminthosporium leaf spot?

Leaf spot / melting out is one of several Helminthosporium diseases which survive in thatch during periods that are unfavorable for disease development. These fungi are most active during periods of cool (60-65°F) and wet weather, but some are able to cause disease whenever temperatures are above freezing.

What does potassium deficiency look like in corn?

Potassium deficiency symptoms in corn appear first on the lower leaves because K is easily moved within the plant from older to younger leaves. Leaf symptoms are a yellowing to necrosis (tissue death) of the outer leaf margins. These symptoms begin at the leaf tip and progress down the margin toward the leaf base.

How do you control brown spots?

Use fungicides (e.g., iprodione, propiconazole, azoxystrobin, trifloxystrobin, and carbendazim) as seed treatments. Treat seeds with hot water (53−54°C) for 10−12 minutes before planting, to control primary infection at the seedling stage.

What does Helminthosporium look like?

Initial symptoms are small lesions on leaf blades. Leaf tissues turn yellow around these lesions. Severely infected leaves may die and appear light tan to straw-coloured. In Couch, Helminthosporium causes dark brown or white “net” blotches on the leaves.

How do you stop the black Sigatoka spreading?

To prevent the spread and establishment of the disease, black Sigatoka resistant banana varieties are the only bananas to be grown in the far northern biosecurity zones (PDF, 334KB).

How do you control yellow Sigatoka?

Management mainly involves chemical control using fungicides like copper oxychloride, mancozeb, chlorothalonil or carbendazim at the prescribed dosage. Fungicide spraying on the foliage and pseudostem should be commenced with the initial appearance and repeated at two weeks’ interval.

What does nitrogen deficiency in corn look like?

year and on soil with low levels of subsoil potassium. Nitrogen (N) deficiency (pictures on front-page) causes pale, yellowish-green corn plants with spindly stalks. Because nitrogen is a mobile nutrient in the plant, symptoms begin on the older, lower leaves and progress up the plant if the deficiency persists.