fact sheet 136 Palms Species and propagation Palm seeds are frequently slow and difficult to germinate under normal nursery conditions. This is partly because the seed embryo is in an undeveloped state before, and even during, the germination process. Palm seeds have a limited lifespan and require specialised conditions of storage and transport to survive. To remain viable, seeds must contain more than 20 per cent moisture. Ideally they should not be subjected to temperatures below 20°C. Viability limits. Three groups are recognised. 2 to 3 weeks viability Bentinekia, Crytostachys, Euterpe, Gronophyllum, Linospadix, Pinanga, Verschaffeltia 4 to 6 weeks viability Caryota, Chamaedorea, Chrysalidocarpus, Laccospadix, Licuala, Pritchardia, Ptychosperma, Roystonea 2 to 3 months viability Syagrus, Howeia, Phoenix Germination requirements Palm seeds need a prolonged period of high temperature (35°C to 38°C) and high humidity to germinate (Table 1). Some germinate more quickly if subjected to 2 to 3 days continuous leaching with water. These include Chrysalidocarpus, Archontophoenix, Chamaedorea, Pinanga, Johannestjesmania, Ptychosperma, Pritchardia, Euterpe. Another method is to leach the seeds for 72 hours in 6 per cent hydrogen peroxide. Licuala grandis and Thrinax barbadensis respond to this treatment. After leaching, keep the seed in seedling trays in sealed plastic bags at a temperature between 35°C to 38°C. Remove germinated seeds when the first shoot is about 1 cm long and plant into small pots or tubes in a 50:50 peat moss and coarse sand mixture without any fertiliser. Table 1. Germination data for selected palm species Approximate germination Scientific name Common name Comments time Archontophoenix alexandrae Alexandra or King palm Archontophoenix cunninghamiana Bangalow palm Presoaking beneficial. Soaking for 72 hours in Archontophoenix spp. 60 to 90 days 100 to 1000 ppm gibberellic acid further accelerates germination Butia capitata Jelly palm 140 to 190 days Remove flesh from seeds and presoak in water Carpentaria acuminata Carpentaria palm 70 to 80 days After seed collection the parent plant dies; Caryota mitis Fishtail or Burmese palm 30 to 149 days suckers continue to grow C. urens Fishtail or wine palm 76 to 198 days As for C. mitis Chamaedorea elegans Parlour palm 60 days C. elatior 118 days C. seifritzii Clustered Parlour palm 50 to 220 days Golden cane, Butterfly or Areca Chrysalidocarpus lutescens 38 to 45 days As for Archontophoenix palm Dictyosperma album Hurricane or Princess palm 30 to 86 days Howeia belmoreana Kentia palm 2 to 12 months Heating beneficial H. forsteriana Kentia palm 3 months to 3 years Hyophorbe lagenicaulis Bottle palm Hyophorbe verschafftii Spindle palm Licuala grandis 50 to 170 days Leach in 6% hydrogen peroxide for 72 hours Presoaking and heating to 25°C accelerates Livistonia australis Cabbage Tree palm 30 to 60 days germination L. chinensis Chinese Fan palm 40 days Neodypsis decaryi Triangle palm Phoenix canariensis Canary Island Date palm 18 to 40 days P. roebelini Dwarf or Pygmy Date palm 30 to 60 days Ptychosperma macarthuri Macarthur palm 50 to 80 days P. elegans Solitaire palm 50 to 80 days Reinhardia spp 60 to 95 days Rhapiophyllum hystrix Needle palm Rhapis spp Lady palms 100 to 130 days Plants usually grown from suckers Syagrus romanzoffianum Queen or Cocos palm Syagrus spp. 60 to 90 days Trachycarpus spp Windmill palm 60 days Veitchia merrillii Christmas or Manila palm Veitchia spp. 30 to 80 days Washingtonia robusta Cotton or Mexican Fan palm Washingtonia spp 30 days © Adelaide Lawnmowers Association Inc S:\1270 - ALMA\Website\Backup\docs\136.doc Page 1of 3 10-Oct-14 Soils and fertilisers Potting mixes should be free draining. A suitable mix is 4 parts composted pinebark, 1 part peat and 1 part coarse sand, with the following fertilisers added (rates per cubic metre): 1.0 kg dolomite lime (to bring the pH to 6.0) 5.0 kg Osmocote® Plus Blue (8-9 month) 16-3. 5-10 2.0 kg Osmocote® Potash Brown (5-6 month) 0-0-36 1.0 kg Osmocote® Coated Iron The additional potash has been beneficial in early growth of palms in trials in California and Australia. At this stage it is recommended to retain the extra potassium for the first two years only. It is popularly believed that palms need high rates of nitrogen. Most palms I encounter with problems have been fed on nitrogen and very little else. Consequently they have a range of nutrient deficiency problems. In the home garden situation, palms are extensively used in coastal areas with soils of high pH. Yellowing of the young foliage is rampant. It stems primarily from iron or manganese deficiency, resulting from the high pH. The best regime for fertilising palms is to apply a general purpose fertiliser about five times a year. If you use a controlled release formulation, three applications may be sufficient. Nutrient deficiencies Listed in descending order of importance Potassium - Symptoms vary but are always on the oldest leaves. Dictyosperma exhibits translucent yellow spots. In other species there is death of the leaf margins or tips or there may be yellowing of the leaflets followed by death of the tips. Necrotic spots or blotches on lower leaves may also be found. Potassium deficiency is quite common. Contrary to popular belief, potassium should be supplied in the same quantities as nitrogen, especially in containers or other highly leached situations. Iron - interveinal chlorosis of new leaves. Chamaedorea may also have necrotic tips and new leaves may not open normally. In palms, iron deficiency is caused by poor soil aeration or by planting too deeply. It is common in Perth coastal areas where limestone is prevalent. Treat with foliar sprays of iron sulphate or chelate. Soil application of iron sulphate may also help. Nitrogen - gradual loss of colour, slower than normal growth, fewer and smaller leaves. In severe cases leaves may be predominantly yellow or whitish. Yellowing or loss of colour is usually uniform over the leaf. Nitrogen deficiency is common. Magnesium - broad chlorotic bands around the margins with yellowing starting at the leaflet tips and travelling towards the base of the leaflets as the deficiency progresses. The yellowing cannot be reversed and treatment is slow. Use of dolomite should prevent this problem. Phoenix spp are particularly susceptible. Manganese - interveinal yellowing of new foliage. The yellow areas later die. In bad cases the newly emerging leaves may be dead and withered except for the base, giving them a 'frizzled' appearance. Common on alkaline soils or under conditions of poor soil aeration or low soil temperatures. Soil application of manganese sulphate may help. Zinc - New leaves show yellowing between the veins in Chamaedorea and Phoenix. In other species yellowing of the new leaves is more general and the leaf tips may die, similar to manganese deficiency. The new leaves are reduced in size. High pH can induce zinc deficiency. Calcium - Chamaedorea and Howeia show deformed new leaves that fail to expand normally. Leaflets die off, to leave only the petiole base alive. Calcium deficiency will eventually kill the growing point of the plant. It should not occur in containers if dolomite has been used. Copper - similar to manganese and zinc deficiency, generally without chlorosis. New leaves reduced in size with necrotic margins. In Phoenix roebelini, new leaves emerge chlorotic and malformed. Not common. Phosphorus - slow growth, no new leaves produced, colour changes slowly to light olive green colour. Caryota turns yellow. Rare. Boron - new leaves become chlorotic and malformed and fail to expand normally. Leaf margins are often necrotic. Flowers abort and blacken. In Chrysalidocarpus, transverse chlorotic streaks appear on new leaves. The streaks eventually coalesce and become necrotic. Sulphur - uniform yellowing of new leaves. Later, the tips of leaflets die. Relatively uncommon. Physiological problems Leaf scorching is common and is often caused by excessive salt levels in the media. This can be a long term problem caused by the gradual buildup of salt in the media. It can largely be prevented by the use of quality potting mixes with good irrigation practices. Reduce the use of fertilisers with a high salt index, such as muriate of potash (potassium chloride) or ammonium nitrate. Use slow release fertilisers with caution in hot weather; some brands and formulations may be more suitable than others. Ensure enough irrigation water is applied to leach excess salts out of the pots, or follow a leaching program once a week or a fortnight. Learn the pour-through method for assessing the electrical conductivity of soil solutions and use it to monitor salt levels. Leaf scorching can also result from transient increases in salinity caused by the media drying out for short periods. This requires a change in irrigation scheduling to prevent the fluctuations in soil moisture that are causing the problem. Often the total amount of water supplied may be quite adequate but it may need to be applied on a more regular basis. For example, irrigate for 10 minutes three times a day rather than 15 minutes twice a day. High temperatures and low humidity can also burn leaves. This can be due to a direct physical (temperature) effect or an indirect physiological (salinity) effect as described above. Some palm species are sensitive to hot weather conditions - shadecloth or some form of overhead misting for cooling may be required. Cold injury is often seen on palms that have been imported from Queensland. Symptoms are the death of large areas of the foliage. © Adelaide Lawnmowers Association Inc S:\1270 - ALMA\Website\Backup\docs\136.doc Page 2of 3 10-Oct-14 Pest, disease and weed control Pests Scale and mealy bug are the most commonly encountered pests of palms. They cause stunting and leaf distortion, leading to decline and eventual death if left untreated.