Unique Seed Quality Problems of sh2 Sweet Corn

The high sucrose content of shrunken-2 (sh2) or supersweet sweet corn inhibits drying of the seed crop in the field, and necessitates a long (70 day +) period of maturation after pollination before harvest and artificial drying of the seed crop. During this time, the ear is highly susceptible to invasion by insects and rotting by fungi. Stringent insect control is crucial for production of disease-free seed. Certain of the ear-rotting fungi, most notably Penicil lium oxalicum, are seed-transmitted, causing disease and mortality in sweet corn seedlings. This necessitates treatment of the seeds with a strong mixture of fungicides, including a broad-spectrum systemic fungicide where possible. During maturation of the seed crop in the field, physiological changes grad ually occur in the seed, rendering it capable of high seed vigor after com mercial harvest and drying. Seed parents differ dramatically in inherent seed vigor, resistance to stress and pests, and in the length of the maturation period needed to produce seed of the highest possible vigor. Commercial seed lots sometimes exhibit poor seed vigor, in spite of high germination. Vigor tests, such as the accelerated aging test, are useful for predicting the field emergence potential of sh2 seed lots.