Location: Application Technology Research Unit
Project Number: 5082-21000-017-01
Start Date: Aug 28, 2009
End Date: Jun 30, 2014
Geranium seed cv. Red Maverick will be sown in Oasis Cubes for ~2 weeks before being transplanted into 6” pots containing soilless medium into either greenhouse or growth chamber environments. Controlled environmental conditions such as light level of 200-400 micromol m-2 s-1 PAR, and temperature at 23 C will be maintained throughout the duration of the study. Other aspects of plant maintenance such as watering, fertilization, and insect control will be implemented as required. The system will utilize computer-based data monitoring and recording of temperature, humidity, light, and soil moisture. Pythium ultimum and P. aphanidermatum will be utilized, and were originally isolated from infected plants and kept in Potato Dextrose Agar (PDA) in Toledo. Tested pathogens will be cultured in artificial media (PDA) for 1-2 weeks prior to inoculation at 23 C. The inoculum density will be adjusted to 104 spores ml-1. The inoculation procedure will be done by adding 100 ml of spore suspension from each of the tested pathogen to each pot. Two major control treatments will be included. One is the negative control where no pathogen will be tested. And the other will include treating of the plants with the fungicide Subdue Maxx prior to adding the spore suspension of each of the pathogen. Periodic response of the challenged plants to treatments will be evaluated using non-destructive techniques which include visual inspection of symptom development and disease severity, chlorophyll content using a hand-held chlorophyll content meter (CCM200), leaf fluorescence with a portable fluorometer (OP-30), soil moisture, and whole-plant gas exchange with a system developed at Ohio State.