Cenchrus longispinus

Abstract: New data concerning the distribution of 41 non-native species for Campania are presented. Acer saccharinum subsp. saccharinum and Jacaranda mimosifolia are reported for the first time in the Italian peninsula and in continental Italy, respectively. Euphorbia pulcherrima is excluded from Italian exotic flora. Using data from field surveys in Campania the naturalization status of Cenchrus longispinus was also updated. Finally, new sites are given for 37 other alien species previously reported for Campania.

Abstract: Summary: Resume: Zusammenfassung Seed dormancy and germination in sand burr (Cenchrus longispinus (Hack,) Fern,) were investigated in laboratory and field studies. The burrs contain two types of seeds which differed in their innate dormancy. Primary seeds formed in the upper spikelet usually germinated within a year. Secondary seeds from lower spikelets germinated slowly and remained dormant for longer periods. Dormancy was enforced at low and high temperatures, and secondary seeds apparently developed an induced dormancy when continuously exposed to high temperatures. More than 94 % of the seedlings established during spring. Light suppressed germination, and secondary seeds also developed an induced dormancy when stored in the light. Burrs sown on the soil surface had an extended period of germination lasting for more than 3 years. However, over 96 % of the seeds sown below the surface of bare soil germinated within 2 years. Deep burial did not enforce dormancy, but germination was suppressed by the presence of live vegetation. It is concluded that treatments which disturb the soil and bury the burrs will stimulate the germination of dormant seeds.

Abstract: Longspine sandbur is a troublesome weed infesting corn in the Great Plains. However, herbicides are now available to control this species. This study characterized longspine sandbur ecology in irrigated corn to aid producers in integrating herbicides into their production systems. Longspine sandbur began emerging May 25, and by June 15, 84% of the seasonal emergence had occurred. Plant development was related to cumulative growing degree days. Seeds were viable early in longspine sandbur's development, with 20% of seeds viable by heading. Producers can minimize seed production of longspine sandbur in field borders by mowing plants at the boot stage. Bur production per plant was related to time of emergence, with seedlings emerging in late May producing 1,120 burs per plant. Seedlings emerging 4 wk later produced 84% fewer burs. Controlling longspine sandbur before 4 wk of interference prevented loss of corn grain yield.

Abstract: Switchgrass (Punicum virgtatum L.) est8blishmeot from seed wu limited by currat-year’s groutb of saadbur [Cmchrus long&pinus (Hack.) Fern.] in tbc Nebraska -. stmd reduction was greater tb8n other w8rm-sason gr8sses seeded 8t the ame time, indk8ting possIbk 8Uelop8thy. Germhutioo studke were conducted to ev8hmte potentkl andbur 8lkloprthy with switchgr8ss. Fresh andbur pknt m8terkl wu cxtr8cted with distilled water for 24 hours. Root, shoot, 8nd whole pknt k8ch8te (2% w/v) from andbur pknts colkcted between the veget8tive 8nd culm eloog8tioo st8p 8nd whok pknt lach8te (2,4% w/v) from vcget8tive or nuture pknts ~8s used. Switchgur germhution ~8s not influenced by root, shoot, or whole pknt lach8te from andbur pknts cornposited over phenolgial st8gen. However, k8ch8te reduced the length of the prim8ry root urd incre8sed shoot length me8sured 8t 11 diys. Generally, the response ‘118s grater with veget8tive andbur compued to mrture 8nd with the higher lachute conceotrcltioo. Whok pknt lach8te (4% w/v) from vept8tive andbur reduced switchgmss germhution compued to m8ture pknt Iach8te. The rehtively rapid development of 8 srodbur cover prior to switchgr8ss seed germirmtion on andy sites mry 8ffect switchgmss germhution 8nd wly root development through 8n 8llelop8thk inter8ctioo. Since tilkge promotea npid andbur development, no-till seedings should be considered for switchon andy soib.