Diseases of Babul:
Babul is attacked by a number of fungi causing much damage. Fomes pappianus Bres attacks injured and old trees, causing the wood to become brittle and crumble away. Other fungi recorded on babul are Phyllactinia acaciae Syd. and Sphaerostilbe acaciae Tilak. Three new species of deuteromycetous fungi, viz. Diplodia acaciae Tilak & Rokde, Cytospora acaciae Tilak & Rokde and Fusicoccum indicum Tassi have also been recorded on babul (Troup, II, 432; Biol Abstr, 1962, 40, 20898; 1966, 47, 58920).
The four most destructive insect pests of babul are Coelosterna scabrator Fabr., Psiloptera fastuosa Fabr., P. coerulia Oliv. and Aeolesthes holosericea Fabr. C. scabrators is a dangerous root borer, whereas, the others strip the bark off the shoots and branches. A holosericea also destroys the wood by tunneling. Babul has been recorded as a new host of Hemaspidoprectus cemereus Green.
The angiospermic parasite, Cuscuta sp. has also been observed on the plant. The timber is attacked by marine borers belonging to the genera Teredo Linn., Martesia Sowerby and Limnoria, which reduce its underwater durability, thus making it unfit for use in marine construction. Babul timber from Maharashtra, tested at different harbours, gave a good rating only at Cochin harbour. Among the grazing animals, goats and camels are the most destructive. Sheep and buffaloes are also harmful; lopping for fodder, as also for thorn hedges, causing much injury to babul.
Diseases of Chrysanthemum Cinerari Folium:
Pyrethrum is susceptible to a few diseases. Fusarium solani (Mart.) Appel. & Wollenw. emend. Snyder & Hansen causes root rot. Yellowing of leaves, wilting, stunting of aerial parts and reduced tillering are the main symptoms which appear during June-July. Infected roots and shoots show black coloration. Partially rotting tillers produce only small buds which fail to open. The tillers die after 2-3 years. To control the disease, the nurseries should be drenched with 0.15 per cent Benlate or Dithane Z-78, or the seedlings should be grown in disease-free soil.
Wilt caused by Phytophthora cambivora (Petri) Buism. and Rhizoctonia solani Kuhn, leads to progressive drying of the leaves and shoots. Puccinia chrysanthemi Roze causes rust, resulting in leaf-blisters. Dusting with sulphur controls it. Infection due to Septoria chrysanthemella Sacc. leads to brown spots with black centre on the leaves, resulting in leaf- shedding. Treating the seeds with hot water (50° for 30 min) and spraying with Bordeaux mixture control the disease.
Species of Alternaria Nees ex Wallr., Aspergillus Mich, ex Fr. and Penicillium Link ex Fr. were isolated from unsterilized seeds of pyrethrum. Surface-sterilization of seeds with mercuric chloride (0.1%) reduces the incidence of Aspergillus and Penicillium. Seed-treatment with Ceresin (containing 1.5% mercury as acetate) at 1:450 by weight of seeds substantially reduces the incidence of the three fungi. Crown rot, collar rot and bud-disease have also been reported. Certain bacterial diseases, as well as infestation by thrips, red spider-mite and nematodes have also been reported on the crop. Spraying Dithiocarbamate, fungicides and organophosphoric insecticides has given good results in their control. In Kodaikanal, no diseases have been recorded.