Emmalea Ernest, Extension Associate – Vegetable Crops; emmalea@udel.edu
Folks at the Carvel Research and Education Center spent a few days this week puzzling over a section of dead plants discovered on Monday in the cantaloupe variety trial. The early theory was that there was some sort of herbicide carryover issue but that didn’t make sense with the field history and some of the symptoms/evidence. After ruling out disease, aliens and sabotage we now suspect that the field was struck by lightning in the violent thunderstorm Georgetown got on Sunday morning.
Both cantaloupe plants and yellow nutsedge in the affected area showed symptoms (Figure 1) – making disease an unlikely explanation of the problem. The affected area is circular and approximately 50′ in diameter (Figure 2). Plant damage decreases as you move away from the center. At the center of the affected area the plastic mulch was damaged and the drip tape was split for approximately 30 ft (Figure 3). Cantaloupe and nutsedge plants near the center of the affected area were completely dead. Cantaloupe plants that were less affected have necrotic stems and necrotic patches on the leaves (Figures 4 & 5). The roots are partially or totally dead. Nutsedge plants had necrotic leaf tips and roots were partially or totally dead (Figure 6).
The cantaloupe trial will be replanted.
Figure 1. Affected cantaloupe and nutsedge plants.
Figure 2. Circular area of damage in the field. Note damaged plastic at the center of the circle and that plant damage decreases toward the perimeter of the circle.
Figure 3. Split drip tape and damaged plastic (replacement tape is beside the split tape).
Figure 4. Cantaloupe plants with varying levels of damage. Plants to the left are from the center of the affected area. The right-most plant is from outside the affected area.
Figure 5. Close up of lightning damage to a cantaloupe plant. Note necrosis from the soil level, up the stems and petioles and out the leaves – presumably the path of the electric current through the plant vascular system.
Figure 6. Three yellow nutsedge plants from the affected area and one from another part of the field. Note damaged roots and burnt leaf tips on the three plants on the left.