In this installment of Detective Dendro, it appeared in the Dec 2005 issue of Arborist News. Old but still good.
The dynamic duo was invited by a staff of Disney's Polynesian Village Resort (about USD 1000 a night, as of Jun 2024) to take a look at their palms. They have been pre-conditioned by a case elsewhere where the crown of a Phoenix canariensis (Canary Island date palm) fell and killed two people. It was later found to be caused by Fusarium oxysporum, which showed signs of withering outside but had actually decayed the insides of the palm.
Even Dendro had to brush up his palm knowledge with a Feb 2005 Arborist News article. The client met them at the entrance of the hotel, and was shown a palm with yellow and frizzy top. Dendro proceeded to get to work by inspecting the base of a Syagrus romanzoffiana (Queen palm), and Codit got on a bucket truck to inspect the crown. There was no signs of fungus. The truck was tapped on, and a very solid sound was heard. Dendro got on the bucket truck after Codit alighted, and realised the problem was not fungal infection such as butt rot, heart rot or Fusarium rot.
The crinkled crown was a sign of potassium, magnesium or manganese deficiency. Older fronds seemed undamaged, so Dendro ruled out magnesium and potassium deficiencies, which affect the older leaves first. The necrotic streaking between leaf veins further confirms that the palm was manganese deficient. The frizzle top is a common problem in many palms, especially Syagrus romanzoffiana, Acoelorrhaphe wrightii, Phoenix roebelenii, Elaeis guineensis and Latania spp. The palms they were inspecting could have endured the manganese deficiency for several months, but if nothing was done, the emerging fronds would get even more curled and stunted, with a withered and scorched appearance. At a later stage of severe deficiency, the palm would die.
The palm at this frizzled state could be treated with foliar or ground application of manganese sulfate. The tree specialist of the estate came by and informed them that she noticed the problem a few weeks ago. She found that the palms were mildly manganese deficient with slightly less than 40ppm, after doing leaf nutrient analysis. If the deficiency had been more severe, or if the soil pH was high, the tree specialist would have used a foliar application. The client inquired if the frizzled fronds would become unfurled, and was replied in the negative. However, healthy and green fronds will grow after the palm's nutrient deficiency was addressed.
Reference: Arborist News, Jun 2024, pages 16, 17 and 73
