Chester is a thornless, semi-erect blackberry prized for its heavy yields of large, sweet-tart berries that ripen in mid to late summer. Its canes are vigorous and require trellising to keep fruit off the ground and improve air circulation — thornless canes make the whole operation considerably more pleasant than thorny cultivars.
Fruit is borne on second-year canes (floricanes), so the annual pruning rhythm matters: remove spent floricanes after harvest, tie in new primocanes, and thin to 4–6 strong canes per plant. Chester is notably cold-hardy and disease-resistant, making it reliable in cooler climates.
Cane Anthracnose
Small purple spots on young canes that enlarge into gray, sunken lesions with purple borders. Severe infections weaken canes and reduce fruit quality.
Prune and destroy infected canes. Improve air circulation by thinning. Apply lime sulfur during dormancy before bud break. Avoid overhead watering.
Botrytis (grey mould)
Grey fuzzy mould on petals and stems, worst in cool wet conditions.
Remove affected parts immediately. Improve air circulation. Avoid overhead watering. Apply copper fungicide if severe.
Crown Rot
Lower leaves yellow and wilt; the base of the rosette turns brown and soft, sometimes with white fungal threads at the soil line. Plants collapse in wet conditions.
Remove and destroy affected plants. Improve drainage and avoid overhead watering. Do not mulch directly against the crown. Space plants for airflow and avoid replanting in the same wet spot.
Japanese Beetle
Popillia japonica →Adults skeletonize leaves and devour petals and buds; aggregations escalate rapidly. Grubs destroy turf in late summer and fall.
Hand-pick adults in early morning into soapy water — beetles are sluggish when cool. Neem oil applied to foliage deters feeding but must be reapplied after rain. For grubs, apply milky spore (Bacillus popilliae) to turf — it takes 1–3 seasons to establish but provides long-term biological control. Beneficial nematodes (Heterorhabditis bacteriophora) applied in late August when grubs are young and near the surface offer faster results. Never use pheromone traps.
Spotted Wing Drosophila
Drosophila suzukii →Soft, collapsing berries with small puncture marks; white larvae inside ripening or ripe fruit.
Harvest fruit promptly and frequently. Remove and dispose of overripe or fallen berries. Use fine-mesh netting or traps. Refrigerate harvested fruit immediately.