Edible Products. 



506 



[December, 1910. 



After the crop is harvested the stubble 

 must also be burned, as the insects 

 pupate in or near the ground. 



Other insect pests to which my atten- 

 tion was called were the leaf-hoppers— 

 Delphax jurcijer and D. strictella — 

 which suck the plant juices; the rice 

 weevil, Calandra oryzce; a Noctuid 

 moth, Nonagria inferens ; a butterfly, 

 Pamphila guttata ; and an aphid, Schi- 

 zoeura sp. Two other leaf-hoppers, 

 Scotinaphora vermiculata and Seleno- 

 phalus cinctieeps, also affect rice, and 

 the latter is supposed to be the means by 

 which one of the fungus diseases is 

 transmitted. 



The following are some of the plant 

 diseases affecting rice in Japan : 1. 

 Stigmonose or dwarf disease. This 

 disease is supposed to be due to punc- 

 tures made by the leaf-hopper, Seleno- 

 phalus cinctieeps. At certain seasons 

 this insect is present in excessive num- 

 bers in the rice fields. As a measure of 

 control, a thin layer of petroleum is 

 spread over the flood water, and the 

 insects are brushed into it and des- 

 troyed. To avoid injuring the rice, the 

 oil is drained off immediately. 2. Bru- 

 sone, a fungus disease causing spotting 

 on the leaves. Often very destructive. 

 The fungus is one of the Mucedinaceee, 

 Dactylaria parasitans, Cav. Remedial 

 treatment consists of thorough tillage 

 and the avoidance of excessive nitro- 

 genous manuring;. 3. Leaf-blight causes 

 considerable damage to the crop in some 

 years, The fungus is one of the H elmin- 

 thosporese, Helminthosporium oryzae, 

 Miyabi and Hori. The remedial mea- 

 sures are the same as those for brusone. 



4. White leaf-blight, probably the most 

 destructive disease of rice in Japan, 

 The losses from it in a single prefecture 

 have amounted to one million yen a 

 year. The Japanese government last 

 year appropriated 3,000 yen for its study, 

 and some promising results have been 

 obtained from these investigations- It 

 was found that the disease is always 

 associated with au acid condition of the 

 soil. A bacterium has recently been 

 isolated from the diseased plants, which 

 is also found in acid soils. It is thought 

 that the bacterium is intimately asso- 

 ciated with the disease. The disease 

 appears to lose its virulence in neutral 

 or alkali soils. 



In connection with this disease it may 

 be interesting to note the painstaking 

 methods of the Japanese scientist, Dr. 



5. Takaishi, Chemist of the Fukuoka 

 Station, who studied this disease in its 

 relation to the soil, discovered that it 

 was always associated with an acid soil, 

 the acidity being produced by excessive 



nitrogenous manuring. He also noticed 

 that the diseased condition spread from 

 the tip of the leaves downward along 

 the margins — the course followed by the 

 dew deposited by the leaves when 

 it was heavy enough to form into 

 drops. Large quantities of dew, in some 

 cases as much as a liter, were gathered 

 and carefully examined chemically and 

 bacteriologieally. Finally, the organism 

 mentioned above was discovered. Pure 

 cultures have been secured and further 

 experiments are now under way. 



Remedial measures for the control of 

 the disease have consisted largely of 

 neutralising the soil and avoiding acid 

 measures. 



5. Rice Smuts. — Two smuts do con- 

 siderable damage to the rice, (1) Ustilagi- 

 noidea virens (Cooke) Tak. with very 

 small spore's; (2) another, Tilletia horrida 

 Tak. with larger spores. Nothing is 

 done to control these diseases except 

 the treating of the seed by dipping in 

 water 130* F., for five minutes. 



The above are only the more serious 

 diseases of rice in Japan. Seventy-six 

 distinct diseases have been recognised 

 and described. 



The introduction of any of these des- 

 tructive plant diseases is perhaps more 

 to be feared than the introduction of 

 insect pests, and it should be a matter 

 of serious concern to our quarantine 

 officers. 



The writer had abundant opportunity 

 to study the disease in the field and in 

 the laboratory ; only lack of pathologi- 

 cal training prevented him from going 

 more fully into the subject, A great 

 deal has been published on these sub- 

 jects, but unfortunately most of it is in 

 the Japanese language. Copies of the 

 more important bulletins were provided, 

 and are submitted herewith. A re- 

 ference was given to a paper entitled 

 " Studies of the Parasitic Fungi of Rice 

 in Japan," by I. Miyake, Bot. Mag. of 

 Japan (Tokyo), Vol. 23, March and April, 

 1909 : but I was unable to secure copies. 



(To be continued.) 



TEA PRODUCTION IN 1909. 



(From the Indian Agriculturist, Vol. 

 XXXV., No. 10, October, 1910.) 



The immense importance and value of 

 the tea industry to India are once more 

 forcibly brought out in the note on Tea 

 Production for 1909, which has just been 

 published from the office of the Director- 

 General of Commercial Intelligence. 

 There were employed on the gardens 

 during the year nearly 600,000 persons, of 



