2. Barren stalks in Ky 203.
In the fall of 1949 a number of farmers fields of Ky 203 were reported to have a higher percentage of barren stalks. The trouble was reported late in the season after the majority of the corn was harvested so it was impossible to get an accurate estimate of the amount occurring but a few fields were observed. The trouble was reported from several locations in the State but most of it occurred in the river‑bottom near Owensboro.
The reports ranged from a trace to 80 per cent barren. Three fields in one locality in which accurate counts were made had an average of 55 per cent completely barren, 19 per cent extremely small nubbins such as would be found for second and third ears of single‑eared hybrids, and 26 per cent ranged from nubbins to good ears. Other fields visited ranged from a trace to about 25 per cent barren and small ears. There was some variation in individual fields as to the amount of barrenness. In some cases there would be 25 to 30 consecutive barren stalks in a row and then several plants with good ears. Often normal ear development occurred adjacent to skips in a row but this did not always hold true. There appeared to be no consistent differences in height or size of stalks between barren and normal plants, except an occasional tall, large dark plant. The darker color was probably due to accumulation of sugars in the leaves and stalks and being overrun with saprophytic fungi. Root systems in all cases were normal. The corn made good growth early and appeared to grow normally throughout the year (although it turned dry following tasseling) and perhaps this is why the trouble was not detected until late in the season.
Many of the stalks showed no indication of having developed a shoot. Others showed evidence of shoot primordia such as for second or third ears. On some plants the shoots were well developed and the silks appeared to have emerged normally but fertilization apparently failed. In these cases the cobs were 4 to 6 inches long but appeared to have disintegrated early and were no larger than a pencil, unlike ears that fail to become pollinated due to lack of pollen. On other plants the cob was only an inch or two long. Some plants were found where the tip of the cob had a few grains but the rest of the cob was shrivelled with no grains.
No other white hybrids were reported to show this trouble but one field of yellow corn, either Indiana 844D or US13, was reported to have a high percentage of barren stalks. This same hybrid planted 2 to 3 weeks later in the same field performed satisfactorily.
Source of seed, use of 2,4‑D, plant population, soil type or fertility could not be established as factors causing the trouble.
Early season conditions were quite favorable for corn but the first half of July was extremely humid in this area and temperatures remained above 90 for an extended period. It is suspected that the high humidity and temperature were factors contributing to the expression of this trouble. The corn may have been at the right stage of growth to develop female sterility under these conditions since corn planted later in the season and under different growth conditions did not exhibit barrenness.
Ky 203 has previously shown pollen sterility as reported by Josephson and Jenkins (Jour. Amer. Soc. Agron. 40: 267‑274. 1948) but the present trouble seems to be an entirely different type of reaction. Neither does there seem to be an incompatibility between silks and pollen since ear shoots failed completely to develop. Ky 203 has been grown commercially for eight years and while a small percentage of barren stalks has been observed previously, to my knowledge it has never occurred on this large a scale.
L. M. Josephson