4 1 8 MAIZE 



CHAP, of the growing season, that the lands remain too soft for 



x 



cultivation, over a long period, and- the weeds are apt to get 



ahead of the maize crop unless other methods of treatment 



are adopted. 



The principal annual weed-pests of the maize crop in South 

 Africa are: mest-briede {Amarantus paniculatus), black-jacks 

 [Bidens pilosa and B. leucanthd), the sweet-grasses [Chloris 

 virgata and Panicum IcBvifolium), goosegrass (Eleusine indica), 

 stink-blaad {Datura Stramonium and D. Tatula), wild goose- 

 berry {Physalis minima), Mexican marigold {Tagetes minuta) 

 and Nicandra physaloides. 



Many other annual weeds occur in the maize fields, such 

 as rooinek (Zinnia pauciflord), burweed [Xanthium spinosum) 

 and kaffir melons [Citrullus vulgaris), but they are less trouble- 

 some than those mentioned in the preceding paragraph. 



378. Volunteer Maize. — Volunteer maize plants may be 

 considered weeds in the sense of our definition. They cross- 

 pollinate plants of the main crop, thus producing " mixed," 

 and consequently inferior, grain. When volunteer plants 

 come up between the rows, they are usually removed by the 

 cultivator ; but it often happens that they come up in the 

 rows themselves, and it is then more difficult to eradicate them. 

 When it is remembered that a single maize tassel may produce 

 from 3,000,000 up to 30,000,000 grains of pollen, that these 

 pollen grains are so light that they may be carried by the wind 

 for a distance of a quarter of a mile, and that it requires only 

 a single grain of pollen to fertilize one grain of maize, it is 

 readily seen that much damage may be done by a single 

 volunteer plant. 



The appearance of volunteer maize is due to several causes, 

 e.g. the planting of different breeds on the same land in suc- 

 cessive years ; the dropping of ears or of loose grains on the 

 land at harvest ; the dropping of undigested grain in the dung 

 of animals working in the fields or pasturing on the stover. 1 



379. How Weeds Spread. — The question sometimes arises 

 as to how weeds get into the lands, and how they spread so 

 rapidly in spite of cultivation. It is often found in the first 



1 The Ohio Station found that 43 per cent of the dry maize grains which pass 

 whole through the alimentary tract of cows will germinate, but none of those 

 which have been ensiled. 



