leaf of currant with blisters on outside, infected with leaf-bunching currant aphid

aphid aphididae aphids aphis blight blister blisters currant damage danger dangerous destructive disease dots foliage fungi fungicide gooseberry grossulariae holding ill illness impairment infected infection infestation insect insects leaf leafbunching man outside parasite parasites pathogen pest pests plant problem sap sick sickness spot spots sucking weakness