- Botrytis: Leaf infections during propagation can cause brown stem cankering and wilting and loss of cuttings. Keep Botrytis under control on stock plants to avoid losses during propagation.
- Phytophthora parasitica: Particularly during the moist conditions that prevail during propagation, stems are rotted and leaf bases show brown decay.
- Rust: Bright yellow-orange sporulation is obvious on the underside of affected leaves, and the upper surfaces show tan leaf spots with a purple rim. Free moisture is necessary for infection, so losses are greatest during propagation.
- Thielaviopsis: Wilting of all or portions of a good-sized plant is typical. Roots may be quite stunted and show areas of very black discoloration. The problem is most likely under conditions of high pH (pH below 5.5 discourages disease development) and in growing mixes that include some mineral soil.