陕、甘、青小麦条锈病发生发展规律之初步研究(续)

PRELIMINARY STUDIES ON THE TREND OF OCCURRENCE AND DEVELOPMENT OF THE STRIPE RUST OF WHEAT(PUC-CINIA GLUMARUM(SCH.)ERIKS.AND HENN.)IN PROVINCES SHENST,KANSU,AND CHINGHAI

四、陕、甘、青小麦条锈病菌的流行传染规律通过前述试验和调查,已找出小麦条锈病菌在陕、甘、青地区主要系在2,000公尺以上的高山山坡及高原地区的晚熟春麦和自生麦苗上的越夏,在陕、甘、青冬麦区各地均可越冬。但病菌夏胞子如何自上述越夏场所传至冬麦区。

It is found in our experiment that the uredospores of the stripe rust of wheat on the plains generally does not survive in the summer over 33 days.on the plains of the three provinces Shensi,Kansu and chighai it can neither pass the summer in the form of uredospores nor on volunteer wheat seedlings.The cross inoculations between the inoculum obtained from the wheat and from the grass weeds of Tai-pai Mountains middle Shensi on the respective hosts were not successful.Negative results were obtained when the wheat stripe rust fungus was inoculated on the impor- tant weeds of the steppes of the three provinces.The stripe rust fungus in this region summering chiefly by the following ways: (1)with uredo-stage on the late spring wheat crop on the vo- lunteer wheat seedhngs on the plateaus and mountain slopes 2,000 meters above the sea level,and(2)on the volunteer wheat seed- lings of the winter crop in the regions 1,400 meters above the sea level. The stripe rust can over-winter invariably everywhere on the winter wheat of this region, but more successfully under conditions such as early sowing,lower grounds, humid and snowy unsunny slopes. The stripe rust fungus is disseminated to the regions of winter wheat from its summering spots by means of west and north west winds.It is first carried by the winds to places where wheat is sown early.The spores produced there will be send further east in to the middle Shensi region and other places where wh- eat is sown late.In the spring it is again carried by east and southeast winds from the regons of winter wheat to those of spring wheat.Upon indentification the pathogenes taken from the two different wheat regions were proved to be identical. Regions where winter wheat is sown early serves not only as a"bridge"during spring and autumn disseminations of the patho- gen,pnt also as a basis for the pathogene during spring.The young volunteer wheat seedlings in regions where winter wheat is sown early serve virtually as a source of infection. On the basis of the trend of occurrence and development of the disease studied in this region,the following principles of control are suggested:(1)in regions of late spring wheat em- phasis should be laid upon the elimination of the summering pa t-hogene;(2)in regions where winter wheat is sown early empha- sts should be laid upon stopping the pathogene from propagation and establishing basis and upon the elimination of summer hosts, and(3)in regions of wInter wheat emphasis should be laid upon lessening the pathogene's chances of wintering.