ABSTRACT
The main task of LSCPP research work is currently efficacy evaluation of plant-protection products for registration in the country. Horticulture trials of fungicides and insecticides are mostly undertaken in apple orchards and to a lesser extent in strawberry, black currant and cherry plantings. A total of 13 fungicides and 11 insecticides were registered for fruit crops in Latvia in 2001. From 1997 trials with apple trees focused on the highly scab-susceptible variety Lobo under fungal disease promoting conditions-near the Baltic Sea-for more precise evaluation of fungicidal efficacy. Under such conditions four to five applications of fungicides were necessary for satisfactory control of apple scab and other diseases. Protective fungicides such as Champion (Cu hydroxide) 50 WP, Effector (dithianon) WG, Euparen-M (tolyfluanid) WG and curative product Chorus (cyprodinil) 75 WG were tested and compared with the standard Dithane M-45 (mancozeb) WP and untreated control. The fungicides were tested in several doses but in all cases proved more effective at higher doses. The aforesaid products were applied mainly in the first protective application and later in the vegetation season, during secondary scab infection. During the primary scab infection period the curative fungicide Score (difenoconazole) 250 EC 200 ml ha' 1 was commonly used. Chorus at 300 g ha-1 proved highly effective in the first application but it is necessary to take into account its comparably shorter length of post application effect. If the next application was delayed, with Chorus treatment scab on the apple leaves spread more intensively than in other treatments. In summer treatments for scab control on the fruits, Chorus
was moderately effective but considerably decreased apple bitter rot extent in storage. Champion at 4.5 kg ha-1 decreased the infected surface of leaves twice better compared to Dithane at 2.4 kg ha-1 given the high scab infection pressure during the first protective application. Such decreased scab infection continued not only on leaves throughout the vegetation season, but also on fruits until harvest subsequent to uniform applications with Score. By moderate scab infection pressure at the time of application Champion and Dithane were similarly effective. Euparen-M at 3.0 kg ha-1 was significantly more effective compared with Dithane in summer applications (the last time 03.08.) in controlling scab and brown rot of fruits. Effector at 0.6 kg ha-1 was similar to Dithane in control of apple scab but more effective in decreasing spread of fruit brown rot.
