Are the leaves stippled with yellow and the foliage is webbed?
Do the leaves and stems have white, cottony clusters on them?
Are the leaves covered with small bumps?
Have the leaves of the young plants been gnawed or eaten whole?
Leaves stippled with yellow and webbed foliage is caused by spider mites. These tiny, spider-like pests feed by sucking sap from the underside of the plant's leaves causing yellow flecking on the upper leaf surfaces. You can control spider mites by spraying plants thoroughly with water 2-3 times a day for several days. For severe infestations, spray plants with insecticidal soap, or pyrethrin as a last resort.
White, cottony clusters on leaves and stems are caused by mealybugs. These tiny insects are covered with a fluffy white coating. They feed by sucking plants sap. They produce the sticky substance honeydew which makes leaves sticky. You can control them by washing them off the plant with water spray. Insecticidal soap should be used with severe infestations.
Leaves covered by small bumps are caused by scales. These tiny, shelled insects often feed on the undersides of the leaves, causing an unhealthy appearance with yellowish blotches on the upper leaf surfaces. Scrape off minor infestations with your fingernail. Prune out badly infested growth, or use a soft brush and soapy water to gently scrub the scales off the stems. Control scales by spraying insecticidal oil during the growing season.
Rabbits and ground squirrels may feed on young Yucca plants until they have become well established. Set up protective barriers around young plants until they have become more established. Bury the bottom of the barrier at least 6-10 inches into the ground. Bending a few inches of the bottom of the fence outward will also help deter rabbits from digging beneath it.
Stem rot causes blackened stems at the base and the toppling over of the plant. These problems are common when plants are kept in a place where too much shade prevents the leaves and soil from drying out. Remove and destroy infected plants and surrounding soil. Let the soil dry somewhat between waterings, and incorporate organic matter to improve soil drainage. Avoid overwatering and overcrowding. Keep winter mulch away from the crowns to prevent excess moisture.
https://plantcaretoday.com/yucca-recurvifolia.html
Wilen, C., Dimson, M., Plant and Pest Guide - Los Angeles State Historic Park, The University of California, Division of Agriculture and Natural Resources
Ellis, B. W., Bradley, F. M., & Atthowe, H. (1996). The Organic gardener's handbook of natural insect and disease control: a complete problem-solving guide to keeping your garden & yard healthy without chemicals. Emmaus, Pa.: Rodale Press.
Sreten null
Hi! I’m Sreten Filipović. I graduated from the Faculty of Agriculture at the University of Belgrade, with a master's degree in Environmental Protection in Agricultural Systems. I’ve worked as a researcher at Finland's Natural Resources Institute (LUKE) on a project aimed at adapting south-western Finland to drought episodes. I founded a consulting agency in the field of environment and agriculture to help farmers who want to implement the principles of sustainability on their farms. I’m also a founding member of the nonprofit organization Ecogenesis from Belgrade whose main goal is non-formal education on the environment and ecology. In my spare time, I like to write blog posts about sustainability, the environment, animal farming, horticulture, and plant protection. I’ve also published several science-fiction short stories.
You can find me on LinkedIn at https://www.linkedin.com/in/sreten-filipovi%C4%87-515aa5158/
