The abundance and population dynamics of onion thrips (Thrips tabaci Lind.) in leek under field conditions
Lithuanian Institute of Horticulture, Laboratory of Plant Protection, LT-54333 Babtai,Kaunas distr., Lithuania, e-mail: l.raudonis@lsdi.lt
Abstract:
In 2003–2005 an abundance of onion thrips (Thrips tabaci Lind.) was investigated in two leek varieties – ‘American flag’ and ‘Campus’- at the Lithuanian Institute of Horticulture. Leeks were damaged by onion thrips every year, but only in 2005 were 100% of the plants infested. In 2003, there were on average 2.2 and 4.2 thrips per plant in ‘American flag’ and ‘Campus’ respectively. Intensity of thrips injury (according to 0–5 points scale) ranged from 1.5 to 1.7 points at the end of the season. Similar patterns were recorded in 2004. In 2005 the mean number of thrips was 13.2 and 13.0 per plant in ‘American flag’ and ‘Campus’ leek cultivars respectively. Intensity of injury at the end of the growing season ranged from 3.4 to 3.0 points. The highest abundance of onion thrips was in late July and early August 2004–2005. Only in 2003 was the maximum number of thrips reached in ‘Campus’ in September. There were no significant differences in the number of thrips between ‘American flag’ and ‘Campus’ leek cultivars. Low and medium correlation between the number of thrips and the incidence of purple blotch (Alternaria porri) at the beginning of infestation was found .
Key words:
Allium porum L., Alternaria porri, Thrips tabaci Lind