{"id":1184,"date":"2016-07-28T16:47:40","date_gmt":"2016-07-28T21:47:40","guid":{"rendered":"https:\/\/www.berger.ca\/en\/?p=1184"},"modified":"2022-07-12T08:53:48","modified_gmt":"2022-07-12T13:53:48","slug":"poinsettia-cultivation-phase-2","status":"publish","type":"post","link":"https:\/\/www.berger.ca\/en\/grower-resources\/hints-and-tips\/poinsettia-cultivation-phase-2\/","title":{"rendered":"Poinsettia Cultivation – Phase 2"},"content":{"rendered":"

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Poinsettia Cultivate – Phase 2<\/h2>\n

By Brian Cantin, Senior Grower Advisor<\/em><\/p>\n

The month of October begins with the transition from vegetative\u00a0growth to bract and flower development in poinsettias.\u00a0Cultural and environmental practices should now be directed towards\u00a0reducing bract edge burn (BEB), a marginal edge necrosis that colored\u00a0bracts are particularly susceptible to.<\/strong> As with many plant maladies,\u00a0to wait until the symptoms are visible creates an unmanageable\u00a0situation. Bract edge burn can be triggered by various environmental\u00a0factors as well as cultural practices. Water stress, temperature fluctuations,\u00a0light intensity, fertilizer regimes, and the percentage of relative\u00a0humidity can all contribute to BEB<\/em>.<\/strong> This is a plant disorder in which\u00a0early preventative measures help to reduce BEB<\/em>. In this article, rather\u00a0than expand on the causes of this disorder, it would be better served\u00a0to focus on the remedial action, i.e., sufficient calcium uptake to support\u00a0healthy cell wall development.\u00a0We often assume that adequate levels of calcium have accumulated\u00a0early in the season in both media and the tissue. This assumption is\u00a0based on the fact that transpiration rates are higher, since temperatures,\u00a0humidity, and light intensity are all conducive to\u00a0calcium uptake by the roots. One has to remember that the\u00a0plant takes up calcium by means of mass water flow.<\/p>\n

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If\u00a0the poinsettia is not actively transpiring due to prolonged\u00a0periods of cool cloudy weather, the uptake and\u00a0mobility of calcium to young developing tissue is\u00a0minimized.<\/p>\n

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Under these conditions, even though\u00a0calcium is present in adequate levels in the root\u00a0environment, due to its lack of mobility, the\u00a0plant will not take up sufficient calcium. Mass\u00a0water flow driven by high transpiration rates\u00a0is the driving force behind calcium mobility.<\/p>\n

Focusing on the issue of calcium in regard to BEB,<\/em> three causes of\u00a0this bract disorder are as follows:<\/strong><\/p>\n

Causes<\/h4>\n