What Is Wrong With My Jerusalem Artichokes?

Do the newly emerged shoots exhibit yellowing of the growing tips which can spread downward over most of the shoot?

Do the leaves have pale areas on upper surfaces and "downy" patches underneath?

Are the leaves pale on their upper side and are there any dusty blisters on the undersides?

Are the leaves covered with white powder?

Are there any white, cotton-like fungal growths around the stem, parts of the plant above it wither and die?

Are the leaves yellow, stems die back?

Apical chlorosis is a bacterial disease caused by Pseudomonas syringae. The pathogen is tuber-borne in Jerusalem artichoke. The shoots that emerge from infested tubers usually become diseased. When necrotic tissue becomes wet, the bacterial cells are liberated and, under favorable conditions for infection, they promote the secondary spread of the disease in the field. Seed stock tubers should be obtained only from fields free from apical chlorosis. It is important to check such fields for the disease before flowering because the symptoms may become less conspicuous as the plants mature.

Pale areas on upper surfaces of the leaves and "downy" patches underneath are caused by Downy mildew. This fungus spreads quickly during cool, wet nights and warm, humid days. Leaves will wilt and die. Remove and destroy all affected plant parts and encourage good air circulation around plants by thining them. Water plants early in the morning to make sure they dry before nightfall.

Likely cause for these symptoms is a fungal disease - Rust. Provide good air circulation around plants by thining them. Avoid making leaves wet when watering. All infected leaves should be removed. Spray leaves with sulfur early in the season to prevent rust or to treat mild infections.

White, powdery patches on the leaves are caused by a fungal disease Powdery mildew. Powdery mildew usually appears in damp places. Encourage good air circulation around the affected plants by thining them and any surrounding plants. Water plants from below to keep foliage dry. Any affected leaves should be cut off and removed. The appropriate fungicidal spray will protect your plant from further infections.

Sclerotinia stem rot (white mold) is a fungal disease that causes these symptoms. Wet weather conditions favor this disease. The disease is usually introduced to non-infected areas by infected seeds. Plant only certified seed. Cereals, corn, or grasses should be used in crop rotations and at least four years should be allowed between successive crops of Jerusalem artichoke and other susceptible species.

Stem borers are small caterpillars that cause stems to die back. As spring growth begins, you can easily spot borer-infested plants because the leaves look weak and sickly. The easiest control is to cut out and destroy infested plants as soon as you notice them.

Large holes eaten into the tubers are usually the work of slugs. These pests are most active in wet summers and on wet and heavy land. A well-kept garden discourages them by reducing the number of places where they can hide. You can trap slugs in piles of rotting vegetable matter which you should inspect daily, destroying any slugs you find. Alternatively, if their attacks are severe enough to warrant it, use a proprietary slug bait according to the manufacturer’s instructions.