Performance of Commercial G. hirsutum Varieties Grown in R. Reniformis Infested Soils with and without Nematicides

Reniform nematode (Rotylenchulus reniformis Linford and Oliveira) currently infests 36% of the Mississippi cotton acres and promotes serious economic losses.    With loss of Temik 15G and soil fumigant expense there is a need for an integrated nematode management program.  This program demands use of a multi-disciplinary approach involving variety characteristics that enhances performance to R. reniformis.  With the absence of R. reniformis resistant varieties, there is a need to better understand how and which commercially available germplasms are providing assistance in these environments.   Studies at Mississippi State University indicated that all varieties evaluated benefitted from the addition of a nematicide.  However these studies showed that some commercial  germplasms offer assistance void of a nematicide and it is this understanding that assists manageing  germplasms grown in R. reniformis  soils.  Field evaluations indicated that plant height was improved with a nematicide.  However, early plant growth of some varieties were less impacted without a nematicide than others and via accumulated internode measurements it was observed that varieties are offering assistance.  Other growth variables like hypocotyl measurements further validated assistance in R. reniformis soils.  Fruit retention was enhanced with a nematicide and at the final evaluation, untreated varieties did show lower retention at fruiting positions one and two promoting a loss of maturity and further observed in the NAWB and NACB observations.  Despite improvements resulting from a nematicide, positive characteristics were observed in commercial varieties evaluated.  Of the five varieties tested, PHY 375 WRF was the most sensitive and responded positively to a nematicide treatment.  Greenhouse studies indicated improved root and shoot using a nematicide in all populations with some varieties being more impacted than others.  It was also observed that as R. reniformis populations increased so did a reduction in shoot and root growth but performance varied especially with PHY 375 WRF.