Epidemiological study of redness on maize

Abstract

Redness as a harmful disease on maize has been present in Banat, as well as in some other regions of Serbia, since 1957. Some years the redness of maize was epiphytotic causing considerable reduction of yield of corn, sometimes over 50%. Redness of maize is a peculiar disease. It appears usually at the beginning of July when maize plants approach tasseling. First symptom can be seen as redness of main vein in the leaves near the ear. Later on redness spreads all over leaf blade, than on upper and lower leaves, as well as on stalk and ear of infected plants. The kernels of disesed maize plants, starting from the top of the ear remain empty (not properly filled) and shrivelled. Infected maize plants wilt and dry up early. From maize plants diseased by redness the fastidious bacteria have been extracted. Those bacteria we found in leaf, kernel and adventive roots. Fastidious bacteria were also extracted from Johnson grass (Sorghum halepense) leaf and rhizome, as well as from leaves of Setaria viridis and Taraxacum officinale plants showing symptoms of redness. Maize plants grown under plastic tunnel (controlled space) from the beginning of June until the end of August were not infected and did not show the symptoms of redness. On the other hand, the most infections of maize plants by the cause of redness took place when maize plants were uncovered during the second half of July. In both years of investigations (2004. and 2005.) the redness was present in the surrounding crops of maize. In 2004 32.0% and in 2005 21.5% maieze plants in neighbousing crops showed symptoms of redness.

Crvenilo kukuruza javlja se u nekim rejonima Srbije. U određenim periodima to oboljenje ima epifitotičan karakter izazivajući značajne štete u proizvodnji kukuruza. Etiologija i epidemiologija crvenila kukuruza nisu razjašnjene. Tokom ovih istraživanja potvrđena je infektivna priroda crvenila kukuruza, kao i prisustvo fastidioznih bakterija u tkivima obolelih biljaka. Kukuruz gajen u zaštićenom prostoru od početka juna do kraja avgusta ne oboleva od crvenila. Najčešće zaraze su u drugoj polovini jula. Fastidiozne bakterija su ekstrahovane iz lista, zrna i pandži biljaka kukuruza obolelih od crvenila, zatim iz lista i rizoma Sorghum halepense, kao i iz lista Setaria viridis i Taraxacum officinaale sa simptomima crvenila.