DISEASES AND INSECTS 



DISEASES AND INSECTS 1033 



CATALOGUE OF DISEASES, continued. 



Pandanus. BLACK CANKER ( Nectria pandani). Kills branches and 

 entire plants. Black pustules on bark oozing black tendrils. 



Control. Cut out diseased portions as soon as noticed. 

 Pansy. LEAP-SPOT (Peronospora violx). Discolored spots with 

 pale violet growth on them. 



Control. Spray with bordeaux mixture. 



Papaver. MILDEW (Peronospora arborescens). Downy mildew of 

 wild and cultivated poppies. Especially injurious to seedlings 

 of garden species. 



Control. Spray with bordeaux mixture. 



Parsley. LEAF-SCORCH (Septoria petroselini). Small scattered 

 brown patches, which increase in size until whole leaf is 

 covered. 



Control. Spray early with dilute bordeaux. Pick off and 

 burn affected leaves. 



Parsnip. LEAF-BLIGHT. See under Celery, Early Leaf-Blight. 

 Pea. MILDEW (Erysiphe polygoni). A powdery mildew on poda 

 and leaves. 



Control. Dust dry sulfur over the plants. 



Peach. BLIGHT (Coryneum beyerinkii). A spotting, gumming and 

 death of the buds and twigs, particularly in the lower parts 

 of the tree. The fruit drops. 



Control. For California conditions, two applications 

 bordeaux mixture, 5-5-50, or lime-sulfur, 1-10, (1) in No- 

 vember or December, and (2) in February or March. 

 LEAF-CURL (Exoiscus deformans). Leaves curl and wrinkle. 



Control. Spray with lime-sulfur, 1-11, beiore buds swell. 

 BROWN-ROT (Sclerotinia fructigena). Rot on fruit and cankers 

 on limbs. 



Control. Spray with self-boiled lime-sulfur, 8-8-50, adding 

 two pounds arsenate of lead. Spray (1) about time shucks 

 are shedding from young fruit; (2) two or three weeks later; 

 (3) one month before fruit ripens. 



SCAB, or BLACK-SPOT (Cladosporium carpophilum). Black scab- 

 like spots on fruit. 



Control. Self -boiled lime-sulfur applied as under Brown-Rot. 

 YELLOWS. A fatal disease. Red spots in fruit. Tuft-like 

 growth of new shoots and finally yellow foliage. 



Control. Burn affected trees. 



Pear. BLIGHT (Bacillus amylovorus). Flowers, young fruit, twigs, 

 and leaves turn black and die. Limbs die back and sunken 

 cankers form in bark. 



Control. Eradicate all wild hawthorns, pears and apples. 

 Inspect and remove all blighted parts of tree. Paint wounds 

 with coal-tar. 



SCAB. Very similar disease to Apple Scab, which see. 

 Pecan. LEAF-BLOTCH (MycosphsereUa convexula). Dark-colored 

 blotches covered with minute black dots on leaves in mid- 

 summer. 



Control. None given. 



Pelargonium. DROPSY. Translucent spotting of leaf. Spots 

 finally die. 



Control. Withhold water until absolutely necessary. 

 Persimmon. ANTHRACNOSE (Glomeretta rufomaculans). Similar 



if not identical to Piper Anthracnose, which see. 

 Petunia. WILT. See under Dahlia. 



Phlox. STEM-CANKER (Pyrenochxta phloxidis). Canker just 

 above the ground on the stem. Plant dies; first turning 

 yellow and then falls over. 



Control. Diseased stems should be removed and burned. 

 Physalis. WILT (Bacillus solonacearum). Pith of stem turns 

 brown, sap-tubes filled with viscid ooze. 



Control. -Get rid of insects such as potato beetle and burn 

 all affected plants. 



Picea. LEAF-SPOT and LEAF-CAST (Phoma sp.). Causes discolor- 

 ation and dropping of needles. Black dots on affected needles. 



Control. Clean up all fallen needles and burn. 

 DROUGHT INJURY. Drying up of needles. Water in dry weather. 

 Pine. ROOT-ROT (Armillaria mellea). Tops turn yellow and die, 

 swelling of trunk at surface of ground. Decay of roots with 

 black threads abundantly present. Toadstools around base 

 of tree. 



Control. Dig up and burn and destroy all toadstools near 

 the affected trees. 



Pineapple. HEART-ROT. Browning of the axis of the fruit, due 

 to excessive moisture at time of ripening. 



Control. Keep down humidity in greenhouses. 

 Piper. ANTHRACNOSE (Glceosporium piperatum). Spots on leaves 

 of plants. Also apple bitter-rot fungus (Glomerella rufomacu- 

 lans) causes similar spots on the fruits. 



Control. Frequent spraying with bordeaux mixture. 

 Platanus. ANTHRACNOSE. See under Oak. Same disease. 

 Plum. BLACK-KNOT (Plowrightia morbosa). Black tumorous swell- 

 ings from 1 to several inches in length, on limbs and twigs. 



Control. Burn all affected parts in the fall. Burn whole 

 tree if badly affected. 

 BROWN-ROT. See under Peach. 



Polygonum. TAR-SPOT (Rhytisma bistortx). Black tar-like spots 

 on leaves. 



Control. Burn affected leaves. 



Pomegranate. INTERNAL ROT (Sterigmatocystis castanea). Central 

 cavity of fruit occupied by a black sporulating fungus. 

 Control. None known. 



CATALOGUE OF DISEASES, continued. 



Pomelo. WiTHER-TiP ( Collet 'otrichum glaeosporioides). Anthrac- 

 nose cankers of stem, spots on leaves and flowers and general 

 wilting of tips of branches. 



Control. Prune off affected parts and spray with bordeaux 

 mixture. 



Populus. HEART-ROT (Polyporus sulphureus). Red rot of the 

 wood, which finally breaks up into cubes. 



Control. Surgery methods. 



Potato. EARLY BLIGHT (Alternaria solani). Circular spots, usually 

 in July and final blighting of whole leaf. 



Control. Spray with bordeaux mixture, every ten days, 

 beginning when plants are 6 to 8 inches high. 

 LATE BLIGHT and POTATO-ROT (Phytophthora infestans). 

 Quick-spreading watery appearing spots in leaves. Mildew 

 on under side. Plants appear as scalded by hot water. Tubers 

 rot in soil or soon after digging. 



Control.-^-Spray with bordeaux mixture, 5-5-50, at least 

 three applications and in wet seasons, six or more may be 

 necessary. Use from forty to one hundred gallons per acre. 

 SCAB (OSspora scabies). A scabby and pitted roughness of the 

 tubers. 



Control. Keep lime and ashes off the land. Soak uncut 

 seed tubers in a solution of formalin, one pint to thirty gallons 

 of water for two hours. Avoid land that has grown scabby 

 potatoes. 



Potentilla. LEAF-SPOT. See under Strawberry. 

 Primula. ROT (Botrytis sp.) Similar to rot of Pxonia, which see. 

 Prune. See under Plum. 

 Prunus. See under Cherry, Plum and Peach. 

 Pseudotsuga. BLIGHT (Sclerotinia fuckeliana). Gray mold of 

 seedlings and younger shoots of older trees in moist situ- 

 ations. 



Control. Spray with bordeaux mixture. 

 Psidium. See under Guana. 

 Pyrus. See under Apple and Pear. 

 Quince. BLIGHT. See under Pear. 



RUST (Gymnosporangium globosum). ^Orange rust of fruit. 



Control. Destroy red cedars in the neighborhood, also 

 wild apples and hawthorns. Spray as for Apple Scab. 

 Radish. WHITE "RUST" or MILDEW (Albugo candidus). A whitish 

 powdery growth on the leaves and petioles, often causing 

 distortion. 



Control. Steam sterilize the soil before planting. 

 CLUB-ROOT. See under Cabbage. 

 BLACK-ROT. See under Cabbage. 



Ranunculus. MILDEW (Plasmopara pygmsea). Downy mildew of 

 leaves. 



Control. Spray with bordeaux mixture. 



Raspberry. ANTHRACNOSE (Glceosporium venetum). Circular or 

 elliptical, gray scab-like spots on the canes. 



Control. Remove diseased canes as soon as fruit is picked. 

 Avoid taking young plants from diseased plantings. 

 CROWN-GALL. See under Blackberry. 



RED, or ORANGE RUST (Gymnoconia inter stitialis). Dense red 

 powdery growth on under side of leaves of black varieties 

 and blackberries. 



Control. Dig up and destroy affected plants. 

 LEAF-SPOT. See under Dewberry. Same disease. 

 Retinospora. GALL (Gymnosporangium sp.). Swellings on limbs 

 and twigs with red-brown pustules covering them. 



Control. Prune off affected parts and keep at a distance 

 from species of Pome. 



Rhamnus. RUST (Puccinia coronata). Irregular yellow blotches, 

 with yellow pustules on under side of leaf. Also on fruit and 

 flowers. 



Control. Keep at a distance from "rusted" cereals and 

 other grasses. 



Rheum. SOFT-ROT. See under Carrot. 



Rhododendron. GALLS (Erobasidium rhododendri). Galls of the 

 size of a pea or larger, at first pale green, then red and brownish 

 covered with white bloom. 



Control. Leaves bearing galls should be removed and 

 burned. 



Rhubarb. SOFT-ROT. See under Carrot. 

 Rhus. CANKER and TWIG BLIGHT (Endothia parasitica). See 



under Chestnut. Causes death of twigs. 

 Ribes. See under Currant and Gooseberry. 



Richardia. SOFT-ROT (Bacillus aroidese). Soft rotting of conns 

 (bulbs) and leaves. 



Control. Change soil every three or four years. Reject 

 corms which show the disease. 



Robinia. HEART- ROT (Trametes robiniophila and Fames rimosus). 

 Heart-wood converted into punk. Shelf-like bodies grow 

 from wounds. 



Control. Surgery methods. 



Rose. MILDEW (Sphxrotheca pannosa). A white powdery mildew 

 on new growth. 



Control. In greenhouses, keep steam-pipes painted with a 

 paste of equal parts lime and sulfur mixed in water. Out-of- 

 doors roses should be dusted with sulfur flower or sprayed 

 with potassium sulfid, one ounce to three gallons of water. 

 STEM-BLIGHT. Similar to Raspberry Anthracnose, which see. 



