Show MOSAIC DISEASE ATTACKS CUCUMBERS X A cucumber mosaic disease produced by transferring to a healt healthy hy plant aphids from a mosaic disease plant note warty and mottled fruits prepared by the united states department of agriculture A new disease of cucumbers cucumber rs known as 03 the mosaic disease has appeared during the past few years in commercial greenhouses een houses and in fields where encumbers cucumbers at are e grown for pickling purposes the disease has been known longest and Is now most widespread ang ani severe in the middle west where the industry ot of growing cucumbers for pickling Is centered particularly in the states of michigan wisconsin indiana illinois and minnesota recent investigations of the disease have resulted in the discovery of its nature that it Is closely related to mosaic diseases of other plants and the present indications are that it can b be e controlled by the introduction of s sanitary measures and insect control methods further experiments with control measures are being carried out appearance of diseased plants the mosaic disease Is commonly known in michigan indiana and wisconsin its as white pickle in minne quite similar in its principal to those found in the field the principal differences being that the disease appears to be more virulent many ol of the inc plants wilting and dying nature of the disease the mosaic disease belongs to tha same class as the mosaic diseases of tobacco potato tomato poke weed and other plants which have been known for some time the exact cause of this class of trouble has not been discovered but it Is considered to be what is known as the hie filterable virus a an 11 agent of infection is so finely divided that it will pass through a porcelain filter and still retain its ability to reproduce the disease when injected into held healthy thy plants the sap or juice of any portion of a diseased vine it injected into a healthy vine will produce the disease the period of cincu bation that is the time which elapses from the inoculation of the vine to the first visible symptoms of the disease la in the greenhouse Is from seven to X t aci 0 V p e ek tying CT y JJ ii g plant in a field badly affected by mosaic disease lead pencil shows relative size of plant note runners very much dwarfed with small wrinkled leaves also very warty fruit sota it is commonly called nubbins bubbins nub bins the disease is characterized in the field by definite plant fruit and leaf symptoms when plants are attacked while very young they are markedly dvar dwarfed fed by the action of the disease growth is slow the runners are very much shortened the leaves are correspondingly spon reduced tit in size the pants pir ants blossom sparingly and the amount of fruit is very much reduced when older plants become diseased the principal visible effects are on the subsequent growth of vines and fruit the vine tips and leaves being dwarfed and mottled and the fruit malformed as described elsea hip tile the leaves of diseased plants are dwarfed often curled and wrinkled and usually have a mosaic or marbled appearance in which areas of light aft ac X A N nw y fruit from plant affected with mosaic disease misshapen with large and small warts of dark green remainder of pickle mottled light and dark green dark green alternate in some cases the leaves brown and die back from the tip the fruits are very conspicuously affected being dwarfed more or less mottled or blotched with ith areas of darker green on a background of light green greenish yellow or almost white la ia the most decided cases the green areas are raised and appear as definite warts or protuberances sometimes of considerable size and the fruits take on many abnormal shapes in some home cases the fruits are a roost most white litte hence the name white pickle this nume name silly Is due to a contusion confusion of this diseased condition with the white while or albino pants arants which typically bear white colored pickles and which have been known to occur occasionally in fields tor for cany years the discoloration and warty londi rendition tion of 0 the fruits often appear on cucumbers not more than at an inch or two long tender render them unfit tor fol pickling purposes so 90 that in addition to the great reduction in yield mused caused by the disease many if not all of ill the faults produced by diseased vines tines are unmarketable la tile the greenhouse the disease lis it fourteen days while lle in the field it Is usually fourteen to twenty five days the agencies of transmission of the disease from diseased to healthy plants are doubtless many it has been definitely proved that plant lice transferred from diseased to healthy plants will carry the disease it is highly probable tal that at other insects will be ba found to act as carriers it Is also practically certain that the disease Is 13 spread by pickers when harvesting the cucumbers control measures judging from the nature of the ease and from the preliminary experiments thus far carried out the remedial al measures indicated by our present knoN knowledge ledge are 1 1 I the eradication or control ot of insect pests which act as aa carriers of the disease and 2 the application of sanitary measures V to eliminate the sources of infection to be most effective these methods must be carried out by all the farmers of a community rigid insect control measures should be started as soon as the plants aro are up and continued throughout the season especially previous to the beginning of picking and all mosaic dl diseased plants pulled and destroyed as aa well as plants with which they have come in contact owing to the tact fact that greenhouse conditions are much more completely under control than field conditions it would seem an easier task to control the disease there As previously stated tor for field control all disease plants should be pulled and destroyed as soon as found and the insects should be eradicated to prevent their spreading the disease |