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Troubleshooting common issues
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Symptom- dark brown or black discolored spot, squishy. Cause- rot. Too wet for too long, too low of temperatures, or other untreated infection gone wrong. Treatment - cut out rot with a sharp knife. Disinfect knife with alcohol before each individual cut. Cut until no discoloration on inner flesh is visible. Dust cuts with sulphur powder and let dry. Reduce moisture, identify and treat causes of the rot.
Symptom- raised blister. Sometimes matches green skin coloring, sometimes black. Can be oozing black. Cause- Oedema, aka “humidity spots” or “humidity blisters”. Roots are drinking and pushing more moisture into the column than the pores on the skin can exhale. Treatment- make sure to wait until the soil is dry beneath the surface before watering again. Make sure humidity is low enough during the day and that there is airflow. Do not treat columns with oil products - can block pores from exhaling properly. Make sure the soil substrate has sufficient air filled porosity and drainage.
Symptom- In seedlings, red coloration all the way around the column showing from the base going up. Tip not red or less red. Cause- phosphorous and/or potassium deficiency. Treatment- use a well balanced fertilizer.
Symptom- yellowish discoloration through the lower portion of the column, all the way around. Cause- nitrogen and/or calcium deficiency. Treatment- Apply a well balanced nutrient fertilizer.
Symptom- yellow or red discoloration focused on protruding portions of ribs, tips, and around areoles, facing the sun. Cause- sunburn. Treatment- provide shade for a few days. Burned areas may scar. Make light reintroductions gradually.
Symptom- white fuzzy clusters on column, around areoles and between ribs. Cause- mealybugs Treatment- isolate affected plants. Remove and discard soil, inspect roots. Scrub mealies away with a toothbrush and alcohol. If you can get it, Imidacloprid.
Symptom- small white or tan scab looking spots with darker centers. Possible cause- scale insects. Treatment- scrub with toothbrush and alcohol. If they easily dislodge, likely scale. If they do not easily dislodge, they could instead be scarring or fungal issues.
Symptom- scarring or small chunks missing from the tip. Cause- “Tip nibbler” class of pests. Grasshoppers, slugs, snails, earwigs, even rodents. Treatment- use a ring of copper sheeting around outside of pots, slugs and snails do not like copper. Check under pots for snails and slugs. Sprinkle Sluggo for snail and slug control, Sluggo Plus adds earwig control. For extreme measures, foliar feeding a mixture of water soluble gypsum and/or Epsom salts will leave a powder residue on plants that tip nibblers do not like. Sometimes you just have to accept that living with your local ecosystem means your outdoor plants will occasionally be food.
Symptom- very tiny speck like insects. Diagnostic- Blow on them. If they jump when blown on - springtails. Springtails are beneficials. Non jumping, fast moving speck like insects that do not fly- predator mites. Other beneficials include worms, spiders, lacewings, ladybugs, praying mantis. Treatment- these are signs of a healthy ecosystem. Leave them be, they will not harm your plants.
Symptom- small discolored specs on column, or a tan crust like area. Cause- “Sucker” class of pest insects. Slow moving speck like insects that do not jump with no flying insects present could be sucker mites. If insects are oblong shaped and flying insects are also present, could be thrip larvae. Use yellow sticky traps to help detect and identify thrips. Also, Aphids. Treatment- Spinosad spray concentrate (Monterey garden insect spray), alternatively flying skull nuke em. These are food safe sprays that will coat the plant and kill any insects that try to suck juice from your column. Apply every 4-5 days, for 4-5 applications to disrupt egg, larvae, and adult life cycles. Only apply at dusk or risk wet droplets of spray magnifying light and causing small black burn marks on columns.
Symptom- skinny new growth at tip. Cause- etiolation. Typically due to lack of sufficient light. Also can happen to cuttings while they are rooting.
Symptom- wobbly columns or seedlings want to tip over. Cause- typically etiolation. Long term insufficient light. You can try to prop the columns up with bamboo skewers or garden stakes, but eventually they will need to be cut and rerooted or logged so they can regrow fatter growth that can support their own weight.