YELLOW PICKLE IN GREENHOUSE CUCUMBERS 



By VICTOR A. TIEDJENS 



Perhaps no other problem causes greenhouse cucumber growers more 

 concern than the appearance of a large number of yellow pickles when 

 the vines should be yielding at their maximum. Whenever plants are weak- 

 ened from disease, poor growing conditions, or a heavy set, yellow pickle^ 

 is always present. Some growers attribute it to degenerated seed, some 

 regard it as mosaic, while others ascribe the condition to lack of pollina- 

 tion by bees. Observations on self and cross-fertilized cucumbers for two 

 generations lead to the conclusion that these assumptions are to a certain 

 extent correct, but the condition is due to many more causes than any 

 one group is usually willing to admit. 



Yellow pickles may be the result of one or more causes such as too 

 heavy a set, poor pollination, the method of growing (whether string or A 

 trellis is used), insufficient soil nutrients, animal or plant parasites, or 

 conditions that weaken growth and stunt the plant. 



The Condition Called Yellow Pickle 



Reference is made to yellow pickle as a condition because it is usually 

 secondary and is brought on by one or more causes. As a rule yellow 

 pickle manifests itself on small cucumbers on old diseased vines, or heavily 

 set vines wliich are in the first set. Occasionally the condition is found in 

 cucumbers from six to eight inches long if the plant has experienced a sud- 

 den shock or "set back." Ordinarily, in the condition known as yellow 

 pickle, the cucumber does not grow beyond a length of four inches. After 

 growth is stopped the cucumber becomes yellow near the stem end, the 

 yellow color gradually spreading toward the tip if decay -does not set in 

 first. Some make suflicient growth to mature a few viable seeds. If suf- 

 ficient growth has not been made to develop viable seed, the cucumber 

 wilts and gradually dries up. 



If it has been fertilized, the yellow pickle may remain on the vine from 

 four to six weeks before it drops off. This condition has been called pre- 

 mature ripening, but differs from that of a normally maturing cucumber in 

 that the yellowing of the mature cucumber becomes visible over the entire 

 surface, the stem end being less pronounced in color than the remainder 

 of the cucumber, a condition directly opposite to that found in yellow 

 l)ickle. Plants may have from one to six or more of these yellow pickles 

 at one time, depending on the set of the plant. A plant having a heavy 

 set may develop only half of the pistillate flowers into marketable cucum- 

 bers, in which case the other half becomes yellow, the proportion of 3^ellow 

 pickles to normal cucumbers depending on the vigor of the plant. A weak 

 plant may mature only one of many pickles fertilized, in which case the 

 percentage of yellow pickle will be very high; whereas, although a strong 

 )>lant under the best growing conditions may not mature all its pickles if 

 the set has been exceptionally large, the percentage of yellow pickle will 

 be relatively small. 



1. There is some confusion in the use of the two terms "yellow" and "white" 

 pickle. The condition here referred to as yellow piclvle may result from any one of 

 several physiological causes and manifest itself in a premature yellowing of the pickle. 



