POTATO DISEASES— POTATO PESTS 



1725 



Remedy 



There is no remedy, and since the 

 plants usually recover quickly, little per- 

 manent injury results. 



Tip Itiirii 

 Sjmptoms 



During protracted dry hot weather in 

 midsummer, the leaves weaken and die, 

 beginning at their tips and margins. The 

 older leaves and those on the lower part 

 of the plants suffer first and worst. This 

 has been a common trouble in Wisconsin 

 potato fields, especially on the earlier po- 

 tatoes. Anything that weakens the plants 

 or injures the foliage increases this 

 trouble. 



Remedies 



Soil rich in humus, good surface culti- 

 vation to keep down weeds and check 

 evaporation, spraying with Bordeaux mix- 

 ture to keep the foliage healthy. 



L. R. .Tones, 

 Madison. Wis. 



Verticillinni Wilt 



Verticillium alboatrum Reink. and Berth. 



This is due to a fungus and is very 

 similar to the Fusarium wilt. The black 

 discoloration of the tuber is much more 

 pronounced than in the case of the Fusar- 

 ium wilt and the wilting is more rapid. 

 It is not so common nor so widely dis- 

 tributed. 



New York Agricultural Experiment StaOon 

 Circular 33. 



Wilt. See Dry Rot, this section. 



POTATO PESTS 



Beet Army Worxi. See Beet Pests. 



Colorado Potato Beetle 



Leptinotarsa decemlineata Say 



A. L. LOVETT 



This insect is fortunately so far not 

 known to be present on the Pacific coast, 

 except in a small area in Eastern Wash- 

 ington and Northern Idaho. That this 

 condition of freedom can long exist seems 

 rather doubtful. There is practically no 

 one interested in potato culture but who 

 knows the vivid examples we have had 

 in the Middle West of what this pest is 

 capable of doing. 



Description 



The adult beetle is of a very robust 

 form. About three-eighths of an inch in 

 length and a little more than half as wide. 

 It is of a dusky yellow color, the wing 

 covers marked with ten longitudinal black 

 stripes. The larvae resemble slugs, but 

 have only three pairs of legs located on 

 the three segments just back of the head. 

 They are of a dark Venetian red, soft in 

 texture and are slimy disgusting looking 

 creatures. The pupal stage is passed in 

 the soil. The pupa is about the color of 

 the larva but shows, the forming legs, 

 wings, etc. The eggs are a lemon yellow 

 and are laid in masses on the leaf, usual- 

 ly on the under side near the mid-rib. 

 They are also deposited on straws, dried 

 roots, etc., which protrude above the 

 ground. 



Both the adult beetles and the larvae 

 feed voraciously on the foliage of the po- 

 tato. The beetle is a fairly strong flier 

 and on warm sunshiny days often takes 

 wing and flies about. The insect passes 

 the winter as an adult beetle, usually 

 hibernating in the soil or in a very well 

 protected spot. They emerge in very early 

 spring and feed on any of the Solanaceae 

 that are handy. They deposit eggs on 

 their host, but this egg-laying extends 

 over a considerable period of time, the 

 beetles depositing more eggs whenever 

 they migrate to a new host. There are 

 ordinarily two broods during each season. 



Remedies 



Where this insect is very bad no 

 remedy will prove entirely efficient, but 

 the arsenical sprays are the standard solu- 

 tion for their control. 



CoM.MON Nematode. See Potato Eel- 

 loorvi, this section. 



False Chinch Bug. See Cabbage Pests. 



Flea Beetle. See Western Flea Beetle. 



Grasshoppers. See Grape Pests. 



Green Peach Aphids. See Aphids. 



Harlequin Cabbage Bug. See Cabbage 

 Pests. 



Hop Flea Beetle. See Cabbage Pests. 



Jerusalem Cricket. See Sand Cricket. 

 this section. 



