Soft Rot. The rhizome turns soft and mushy and usually very foul smelling. The entire clump 

 may be killed if the rot is not checked. The bacteria which cause the rot are present in most soils, 

 but only attack through injuries. Usually serious only under warm, humid conditions. Control: 

 Often can be checked by cutting off the affected "toe" or by scraping out the rotted tissue and 

 drenching with a 1 to 1000 solution of bi-chloride of mercury (1 8-grain tablet to a pint of water) 

 or a concentrated solution of potassium permanganate. Control of iris borers (see below) is 

 important since rot bacteria may enter through borer injuries. Be sure that the plants receive 

 plenty of ventilation and sunlight 



Botrytis Rot or Winter Rot. The rhizome is covered with an olive or black felt-like fungus 

 growth. Little or no new spring growth develops and the plant dies. Roots and parts of the 

 rhizome may be rotted. Control: Remove all diseased "toes" and soak remaining divisions 5 to 

 10 minutes in calomel suspension (1 oz. calomel to 1 gallon water). Do not replant in infested 

 soil unless it is first sterilized. Use only light mulches and remove them early. 



Heterosp orium Leaf Spot. Abundant, regular, tan-to-brown spots on leaves, causing them 

 to look unsightly and die back prematurely. Rhizomes not attacked. Spores spread by splashed 

 water. Very common in rainy areas. Control: Remove all infected leaves and cut back green 

 leaves below infections in the fall; burn this material. Spray or dust thoroughly with a zineb- 

 containing mixture about once a week as long as active leaf growth continues. (The composition 

 of pesticide sprays and dusts is always printed on the label.) 



Bacterial Leaf Blight. Irregular brown spots with water-soaked margins on leaves. Bacteria 

 spread by splashed water. Sporadic in occurrence; serious only in wet seasons. Control: Remove 

 and burn infected leaves. 



Scorch. Leaves turn reddish brown and die back. Center leaves often affected first Entire 

 top growth may die down but rhizome not visibly affected. In late stages the fleshy parts of the 

 roots rot, leaving only the central core and the outer sheath or "skin." Control: No definite control 

 known. Affected plants sometimes "recover" when aU old roots are removed and rhizome is 

 thoroughly dried before replanting. Scorch is sporadic in occurrence, but may occasionally 

 cause serious losses. 



Iris Borer. First appears as small holes and tunnels in leaves running down toward rhizome. 

 Later, the borer may enter the rhizome, eating away much of the tissue and often providing 

 entry for soft rot bacteria. Eggs laid in fall by the adult (a moth) in old iris refuse and in the 

 soil near iris plants. Control: Remove and burn all old iris leaves and other debris in fall or 

 early spring to reduce carry-over of eggs. Spray or dust foliage weekly in spring and early 

 summer with mixture containing DDT, malathion and zineb (for fungus leaf spot). 



Above information on Culture of Iris is by William G. McGarvey and that on Pests and Diseases by Dr. A. W. Dimock 

 and are reprinted from the Bulletin of the American Iris Society for July, 1959. 



HOW TO DIVIDE AND PLANT AN IRIS 



After about 3 or 4 years an old clump should 

 be dug up and divided. Healthy, growing 

 rhizomes are separated from old bloomstalks 

 and weak, wornout portions discarded. Wash 

 rhizomes thoroughly before replanting. Best 

 time to do this is July, August or early Sept. 



Before planting a new bed 

 of Iris, dig in plant food and 

 cultivate well. When ready 

 to plant, dig two slanting 

 holes, leaving a dividing 

 ridge in the center. 



Place the rhizome direct- 

 ly over the center of the 

 ridge and spread the 

 feeding roots to either 

 side, so the plant is se- 

 curely anchored. 



Pull dirt towards plant 

 from either side. By 

 pressing on top of root, 

 proper planting depth 

 may be regulated. Firm 

 with foot and water well. 



