Q. I have a Canary Date Palm that developed yellowing leaves last year. I planted this palm about 10 years ago in my landscape. Canary Island Date Palm A. The proper name is Canary Island Date Palm. Eliminate simple possibilities first.  Water and drainage Make sure whatever method you are using to irrigate the tree has not changed because of a broken irrigation line or malfunctioning irrigation emitters. Check the soil around the tree to make sure it’s not still wet before it is irrigated the next time. The soil at four or 5 inches deep should still be starting to dry when you water again. Watering cycles of palms is similar to other large trees on your property and not to other locations like lawns, flowerbeds that require frequent irrigation. Watering palm trees as frequently as you would these locations would be a mistake. Fertilize with a palm fertilizer Palm nutrient deficiencies such as potassium, magnesium or manganese deficiencies can cause yellowing as well. Use a palm tree fertilizer such as Arizona’s Best the next time this palm tree is fertilized. Disease Possibilities There are a couple of disease possibilities that have not yet, to my knowledge, been diagnosed in southern Nevada. Three palm diseases have been noted in Southern California on this Palm. The only disease which causes fronds to yellow on Canary Island Date Palm is Fusarium Wilt. This disease can be spread from tree to tree through pruning tools. Wiping or spraying the cutting blades of pruning tools with at least 70 – 90 % isopropyl alcohol will effectively keep the disease from being spread due to a lack of sanitation to other palms. Anyone pruning these palms should never use dirty tools. Tools should be cleaned with soap and water first and then sanitized before pruning begins.