BLUEBERRY CULTURE 13 



Third, remove the shorter, weaker shoots to prevent crowding. 



Fourth, cut back shoots with too many fruit buds. Three or four such buds 

 on a shoot are enough because each bud produces a cluster of eight to twelve 

 berries. If more buds are left, so many berries will develop that they will be small. 

 Since some \arieties, such as Cabot, grow many fruit buds relative to the number 

 of leaf buds, their shoots must be cut back half to two-thirds. In Fig. 7 the three 

 shoots on the right illustrate this condition. Other varieties such as Rubel, pro- 

 duce fewer fruit buds and need little or no cutting back. This is the condition 

 of the three shoots on the left in Fig. 7. 



Final!}-, stud\ the needs of the plants. Cut freely to encourage new growth. 

 If pruning for the first time, seek expert advice. 



Insects and Diseases 



The cranberry fruit worm, Mineola vaccinii Rile>- (5), sometimes attacks blue- 

 berries. It has become a serious pest of this fruit in Michigan. The mature 

 worm is about half an inch long. It has a \ellowish head and a green body some- 

 times tinged with red on the back. It often webs several berries together and 

 works among them. It probabh" can be controlled by applying a derris dust 

 (2 percent rotenonc), at the rate of 100 pounds per acre toward the end of the 

 blooming period. 



The cranberry weevil, Anlhonomus musculus Say, is sometimes a serious blue- 

 berry pest. The adult is a long-snouted beetle similar to the plum and apple 

 curculios but smaller. The larva, about one-ninth inch in length, is a whitish, 

 legle^s grub with a yellow head. The adults injure the flowers somewhat but 

 the grubs do more harm in the berries. This insect can be controlled by spraying 

 in the spring after growth starts but before egg laying begins, usually about May 

 10, with Bordeaux mixture and calcium ar-senate made up as follows: 



Stone lime 10 pounds 



Copper sulfate 6 pounds 



Water 100 gallons 



Calcium arsenate 6 pounds 



Fish-oil soap 4 pounds 



The blueberry stem borer, Oberea myops Hald., (4) sometimes damages the 

 bushes considerably. The beetles (Fig. 8B) lay their eggs (Fig. 8C) in young 

 shoots about six inches from the tip. The female girdles a shoot in two places 

 about half an inch apart and deposits an egg in a slit in the bark between these 

 girdles. The tip of the shoot then dies, turns brown, and often breaks off at the 

 top girdle (Fig. 8A). When the egg hatches, the young larva bores down the 

 center of the shoot (Fig. 8D). It continues this boring for two or three years and 

 may even reach the roots. The infested stem usually dies (Fig. 8E). If the borer 

 gets into the roots, it weakens the whole plant and the leaves turn yellowish 

 or reddish. 



This insect can be largely controlled b>' having the pickers break or cut oft' 

 the dead tips while gathering the fruit. If the egg has hatched and the larva 

 has started to bore, the shoot should be cut off below the lower end of the tunnel. 

 Infested stems missed in the summer will usualh- be found during pruning the 

 following winter and should be removed then. As the larva is a legless grub and 

 cannot crawl back to the bush, the infested shoots may be dropped on the ground. 

 When the borers get into the roots, a piece of baling, wire shoved down the tunnels 

 will kill most of them. 



