STAR (Strobilurin Type Action and Resistance) fungicides include the strobilurins – azoxystrobin, dimoxysrobin, enestroburin, fluoxastrobin, kresoxim-methyl, metaminostrobin, orysastrobin, picostrobin, pyraclostrobin, and trifloxystrobin, and the non-strobilurin – famoxadone, fenamidone and pyribencarb with similar mode of action. They were introduced in the late 1990s and represent a novel group of fungicides.

They are mitochondrial respiration inhibitors (MRI), which inhibit fungal respiration at Quinone “Outside” (Qo) binding site of the cytochrome bc 1 complex. As such, they are also known as quinol oxidation inhibitors or Qo Inhibitotrs or QoI fungicides. They are highly effective against a broad range of fungi belonging to Oomycetes, Ascomycetes, Basidiomycetes and Deuteromyctes. Several solo and coordinated products of these fungicides are available worldwide. For latest updates visit the website http://www.xsgrowth.com .  Because of their unique mode of action and controlling diseases caused by all the four group of fungi,   the group has attained stardom status in the realm of fungicide world. Being site-specific, they are also at risk from the development of resistance in the target plant pathogens.

STAR fungicides are not cross resistant with other fungicide groups but there is a cross resistance among all active ingredients within STAR or QoI fungicides. Resistance development can, however, be staved off following the resistance guidelines provided by FRAC, which emphasizes the following key points:

1.     In cereal crops the number of QoI containing sprays must not exceed two

2.     QoI products must always be used in combination with a product, other than QoI, recommended for the control of same disease.

3.     QoI product should be used preventively or as early as possible in the disease cycle keeping aside reliance on curative ability.

It is therefore imperative that all users of STAR fungicides adhere to the latest resistance management guidelines available from FRAC to exploit the full potential of this group of novel fungicides, which created sensation with their discovery.