Research Report: High Tunnel Tomato Fruit Cluster Pruning

Tomatoes are a high value crop grown worldwide. Indeterminate varieties are commonly grown in high tunnel structures throughout New England for the fresh market. Indeterminate tomato plants often suffer from a phenomenon called ‘June drop’ in which the plant’s first four to five cluster of fruit set perfectly but the subsequent two to three clusters have poor set and plant productivity drops suddenly. While cluster thinning (e.g., reducing the number of fruit allowed to mature per cluster) has been successfully shown to increase fruit size, it has generally not increased marketable yield. We hypothesized that reducing the fruit load by thinning clusters OR removing alternate clusters could reduce the stress placed on plants, and therefore permit more sustained fruit production throughout the season. We compared five fruit cluster-pruning treatments: control (no fruit pruned), 6 (six fruit per cluster), 3 (three fruit per cluster), 6A (every other cluster removed and six fruit per remaining cluster) and 3A (every other cluster removed and three fruit per remaining cluster). Compared with plants that were not cluster-pruned, removal of alternate clusters did produce more consistent fruit production, but overall yield was lower than for unpruned plants. Cluster pruning treatments increased fruit size, but cracking incidence increased as fruit size increased. Vegetative growth was significantly increased by reducing fruit load; however, this was not correlated with greater yields and required additional labor for increased trellising and sucker removal. Results from this preliminary experiment did not suggest that removing alternate fruit clusters is beneficial