SUSCEPTIBILITY OF THREE WHEAT CULTIVARS TO MITE INFESTATION AND SOME MITE CONTROL MEASUREMENTS IN WHEAT FIELDS AT SHARKIA GOVERNORATE

The present study includes three points, i.e., wheat cultivar
susceptibility, seasonal fluctuation of mite species, associated predators and
evaluation of certain control materials against mites on wheat plants.
The susceptibility of the three wheat cultivars (Sakha 93, Giza 168 and
Gemiza 9) to investigation of mite species Petrobia tritici Kandeel, El-Naggar
and Mohamed and two spotted spider mite, Tetranychus urtica) was inspected
during the two successive seasons of 05/06 and 06/07 at Zagazig district. The
obtained results revealed that the Sakha 93 cultivar was more susceptible to
P. tritici infestation. The relatively higher numbers ranging 9.37- 11.26 and
2.142-8.18 mite/leaf were recorded for the two mite species during the two
seasons, respectively. The relatively lower mean numbers ranged 4.47-5.37
and 1.76-4.47 mite/leaf were recorded on Giza 168, while the moderate
numbers of 6.36-8.47 and 2.08-4.7 mite/leaf were recorded on Gemiza 9
cultivar for the two mite species during the two study seasons.
The yield of test cultivar was found in contrast with infestation levels,
where the relatively lower yield ranging 3.68-4.0 g/plant was recorded for the
more susceptible cultivar, Sakha 93; while the highest yield ranging 6.0-6.02
g/plant was recorded for the more tolerant cultivar, Gemiza 9 which infested
by moderate number of mites.
The result of seasonal fluctuation of the mite species infested the three
tested cultivars revealed that the population of P. tritici recorded 1-2 peaks
during the two seasons with the highest mean numbers of 28.0 and 34.33
mite/leaf on Sakha 93 at the first weak of April during the two seasons,
respectively. The two spotted spider mite recorded 3-4 peaks on the tested
cultivars during the two seasons with highest peak of 26.0 mite/leaf on Sakha
93 at early-April during the first season. During the second season, the
highest peak of 7.0 mite/leaf was recorded at the end of March on Gemiza 9.
The relatively higher total predators number ranging 7.33-11.67 and
3.0-6.33 individuals/plant were recorded in timing with the high number of
phytophagous mites on tested cultivars during the first and second seasons,
respectively.
As evaluation of toxicant materials results, the all tested materials
reduced the numbers of mites significantly compared with control with highest
reduction percentages recorded for the convention pesticides followed by
plant extracts and other materials.
Regarding to reduction percentages, three groups were conducted, the
first ranging 78.84-96.55 % (pesticides), 70.94-88.23 % (plant extracts) and
45.24-69.93 % (bio-products) during the two study seasons. Therefore, it
could be concluded that the plant extracts and bio-products can be used as
control agents for mites IPM programs in wheat fields.