PPDL Picture of the Week

March 7, 2016

Healthy transplants: Healthy beginning

Dan Egel, Extension Plant Pathologist, Southwest Purdue Agricultural Center


The photo that accompanies this article shows a tray of watermelon seedlings that are ready to be transplanted into a field or garden.  Every effort should be made to plant only healthy seedlings to avoid the unwanted introduction of diseases and insects.  These seedlings should be inspected for leaf spots and other symptoms that may indicate a disease or insect pest.


Overall, the leaves of the watermelon seedlings in this photo seem pretty healthy.  However, there appears to be something wrong with a few of the seedlings.    Several of the seedlings are smaller and wilting.  Does this indicate a disease?


We are all familiar with plants that wilt due to lack of water, however the soilless mix in the tray used does not appear to be dry.   Since some diseases and feeding from insect damage also cause plants to wilt, samples could be sent to the Purdue Plant and Pest Diagnostic Laboratory for diagnosis.  Isolation from the stems of these plants would identify Fusarium wilt as the cause of the wilt.


In a few weeks, retail garden stores will start to sell vegetable seedlings for home gardens.   In addition to avoiding seedlings with leaf spots, buyers should also avoid wilted plants.   The cause may be more serious than lack of water. 


Click image to enlarge


Several of the watermelon seedlings in this photo are wilted due to Fusarium wilt.