CARBOHYDRATE PARTITIONING, CULTURAL PRACTICES, AND VINE DECLINE DISEASES OFCUCURBITS

Authors: Bruton, Benny; Russo, Vincent; GARCIA-JIMENEZ, JOSE - UNIVERSIDAD POLITECNICA; MILLER, MARVIN - TEXAS A&M UNIV.

Submitted to: Cucurbitaceae Proceedings
Publication Type: Review Article
Publication Acceptance Date: 8/20/1998
Publication Date: N/A
Citation: N/A

Interpretive Summary: Cucurbit vine declines have become more widespread and yield-limiting in many production areas of the world. Vine decline in cucurbits can be caused by many different organisms. The common characteristic of vine declines is that the plants typically appear healthy until one to two weeks prior to harvest. The plants begin to yellow and decline exposing the fruit to sunburn and consequently the fruit are unsalable. The prevailing theory is that the vine decline diseases are more severe in hybrid cultivars. This review explores many possibilities for the increased incidence and severity of vine decline in the last twenty years. We address the diversion of photoassimilates from the roots to the fruit following fruit-set which results in a reduction in the rate of root growth and increased susceptibility to fungal pathogens. Coincident with the introduction of hybrid cultivars have been many changes in cultural practices such as plastic mulch, drip irrigation, transplanting, and increased plant population. We propose that while these cultural practices have been positive for increased yields and fruit quality, some of the practices have contributed to the increased severity of vine declines.

Technical Abstract: Cucurbit vine declines have become more widespread and are yield limiting in many production areas of the world. Coincident with the increased number and severity of these diseases has been many changes in cultural practices that include inadequate rotation, transplanting, plastic mulch, trickle irrigation, increased plant density, and the use of improved hybrid cultivars. The prevailing theory is that the vine decline diseases are more severe in hybrid cultivars, as opposed to open-pollinated cultivars, because of a heavier fruit-load that places the plants under added water stress as the fruit near maturity. We propose an alternative hypothesis. Specifically, we believe that the severity of crown rot and root rot vine declines is, in large part, due to carbohydrate re-allocation from the root to the fruit following fruit-set. Further, we believe that some current cultural practices play a role in predisposing plants to disease development.