whole plant, such as Maryland, 

 the yield and quality may be re- 

 duced by premature ripening of 

 the lower leaves. 



INFESTATIONS 

 How They Start 



Aphid infestations in tobacco 

 may start in the plant bed or in 

 the field, depending on the condi- 

 tion of the winter and spring host 

 plants. 



In the Connecticut River Valley 

 area, aphids normally spend the 

 winter in the egg stage. During 

 the spring season winged forms 

 are produced and fly to other food 

 plants. They may infest tobacco 

 plant beds and fields. 



In Tennessee and Kentucky, few 

 aphids survive the winter. Plant 

 beds of burley and dark fire-cured 

 tobaccos usually are not infested 

 by aphids from the local winter 

 host plants, but they may be in- 

 fested lightly in May by winged 

 aphids from other areas. Field 

 infestations early in the season 

 are light also, and the aphids do 

 little damage before the plants 

 are topped. 



In central and northern North 

 Carolina and in southern Virginia, 

 most of the aphids spend the fall 

 and winter on garden patches of 

 collards and turnips. A plant bed 

 near these patches usually will be 

 infested. Under the cover, where 

 it is warm, the aphids multiply 

 rapidly. They are carried to the 

 tobacco field on the seedlings. 

 Most of the heavy infestations in 

 the field are started in this way. 



In South Carolina and southern 

 North Carolina, aphids winter on 

 garden patches, as they do in cen- 

 tral and northern North Carolina 

 and in southern Virginia, and 

 they start some plant bed infesta- 

 tions. In these areas, however, 

 most of the aphids that infest 

 tobacco come from extensive 



growths of wild mustard in grain 

 and clover fields and in pastures. 

 Large numbers of aphids feed on 

 the mustard in late winter and 

 spring. The mustard matures 

 about the time that tobacco is set 

 and many tobacco fields are in- 

 fested by aphids flying from the 

 mustard, especially when tobacco 

 is planted near mustard. 



In Florida and Georgia, both 

 plant beds and fields may be 

 heavily infested by aphids flying 

 from fields of wild mustard or 

 cultivated greens. 



How They Develop 



Aphids reproduce quickly on 

 young tobacco in the field, espe- 

 cially in the shade. They are most 

 numerous on the underside of the 

 lower leaves of tobacco plants, but 

 a great many may be found also 

 on the youngest leaves near the 

 tip of the plant. When they are 

 abundant, they cover almost all 

 the leaves. 



In Virginia, the Carolinas, Geor- 

 gia, and Florida, they increase 

 rapidly for a month or more in 

 the field, but they do not thrive 

 after hot weather begins. When 

 the temperature reaches 90° F. 

 3 or 4 days in succession, large 

 numbers of aphids die and turn 

 black. Some may remain in shady 

 spots, but few are seen elsewhere 

 unless the weather becomes cool. 

 When aphids infest the plant beds 

 early or where large numbers of 

 aphids fly into tobacco from mus- 

 tard fields, they may become 

 abundant enough to injure the 

 plants before hot weather begins. 

 Unshaded fields that are lightly 

 infested early in the season are 

 not likely to be injured unless 

 weather conditions are especially 

 favorable for aphid development. 

 On cigar-wrapper tobacco, which 

 is grown in the shade, aphids in- 

 crease so rapidly that damage 

 may occur at any time. 



