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Different sulfur compounds can be used as well . There are several iris diseases with similar symptoms that can occur when iris borer is absent , including bacterial soft rot , iris scorch ( probably caused by a phytoplasma ) , and fungal leaf spot ( Didymellina macrospora ) . Since earthquakes do not recur with sufficient frequency to acquire the necessary data in a single location , we must resort to what might be termed an " ergodic " hypothesis and study earthquakes worldwide , with the idea of recognizing patterns associated with broad sets of geological and tectonic circumstances , which presumably apply to other similar areas . Insects and diseases are not likely to cause problems with most plantings . At the present time , no such data sets exists , and no system is in place to provide it . Insects and Diseases Apple Pests Apples are hosts to many insects and diseases . In principle , all three compo-nents of surface displacement could be obtained from space ; in practice , we are only likely to obtain at most two , if data from both the ascending and descending passes of the satellite are available . Finally , an issue has only recently emerged as a critical one - - the need for properly georeferenced data sets at all stages . However , many questions remain before routine monitoring of the world 's active volcanoes with SAR interferometry can be considered . Clematis is subject to infection by several diseases including powdery mildew ( Erysiphe ploygoni ) , crown gall ( Agrobacterium tumefaciens ) , and various leaf spots ( Cercospora squalidula , Septoria clematidis ) . Management of insects and diseases is called Integrated Pest Management ( IPM ) .