a. F ruit growing (E . Schadegg) Apple scab (Venturia in aequ alis)
In 1985 infection by apple scab was not as severe as in previous years.
In two experim ents the benzim idazol com pounds w ere com pared with th e ergosterol inhibiting com pounds. T he benzim idazol com pounds had the p o o rest effect, particularly in th e experim ent which had given reason to suspect a benzim idazol resistance.
In three o th er experim ents different types of com pounds against apple scab w ere tested.
The ergosterol inhibiting com pounds had, as in previous years, the best effect.
Best effect w as obtained with T opas C 50 W P, but th e com pound also caused the highest russeting index num ber. R ubigan gave excellent effect as leaf fungicide, but the p ro tectio n of th e fruits was not as good as th at of the leaves. This is in accordance w ith results from previous experim ents. C ap tan fl. also had good effect against apple scab and the russeting index num ber was very low. T h e effect obtained w ith benom yl was also insufficient in 1985, but the effect was a little better than previous years, however, w here the infection by scab was m ore severe.
S. 33086, which is an ergosterol inhibitor, was approved for control of apple scab.
P ear scab (Venturia p irin a)
The infection by p e a r scab in the u n treated experim ental plots was so w eak that the experim ent could not form the basis for an evaluation o f the tested products.
Blossom wilt (M o n ilia laxa) in cherries
The severe infections by blossom wilt in sour cherries provided the possibility of testing o th er types o f fungicides than the benzim idazol products. 3 experim ents were carried o u t in sour cherries, K elleris 16, in a orchard in N agelsti near Nykøbing F. and in R oneklint near P ræ stø. A lthough the experim ents did not give a clear result, b o th the dicarboxim ides and the ergosterol inhibitors, Saprol, Rubigan, B aycor 25 W P, T opas C 50 W P and R ovral m ay com e into consideration as substitutes for th e benzim idazols.
Leaf spot a n d sh o t hole (Blum eriella ja a p ii)
In 1985 tests w ere started of products against leaf spot and shot hole. T he first spraying w as carried out on 20th M ay followed by sprayings after each period
w ith rain, 6 tim es in all. T he experim ent showed that pro d u cts which are effective against apple scab are also suitable for control of leaf spot and shot hole.
T he tested products w ere Baycor 25 W P, Rubigan, T opas C 50 W P and D elan d SC 750. In 1986 the intention is to test m ore products. T he establishm ent of a u niform infection in the cherry plantation o f the R esearch C e n tre for Plant P ro te c tio n was successful.
C a n k e r a n d eye ro t (N ectria galligena)
A t th e R esearch C en tre for P lant P rotection an experim ental method has b e e n tested, which may form the basis for testing com pounds against canker an d eye rot: O n each tree (= replicates) 10 random shoot ends w ere selected and cut o ff w here they had the thickness o f a pencil.
In the preventive experim ents the trees w ere sprayed o n 19th Ju n e and 21st J u n e and infected with a spore suspension with 7.9 x 10 sp o re s/m l. In the curative experim ents the shoot ends w ere dam aged and infected on th e same day (1 9 /6 ).
T he com pounds w ere applied on 27th June. O therw ise, th e m ethod used w as th e sam e as th at of th e preventive experim ents. T he assessm ent o f the experim ents took place 5 m onths after the treatm ent, when the length o f the lesion w as m easured. N o significant differences w ere found in th e effect o f the 3 com pounds tested, but the susceptibility o f the cultivars differed significantly, however.
T h e experim ent showed that it is possible to infect apple trees artificially w ith canker and eye rot. F u rth er tests should be m ade of th e m ethod, in w hich f.
inst. ano th er tim e for causing the lesion and the infection is chosen, w hich provides a b e tte r clim ate for the fungus. T he advantages of this inoculation m e th o d is th at the assessm ent of th e results is easy and precise.
W in ter m oths (C h eim atobia spp.) to rtrix m oths (Tortricidae)
In 1985 th ree experim ents w ere carried out on control o f w inter m oths and to rtrix m oths, it was a mixed population, th e m ajority being tortrix m oths, however. In all th ree experim ents th e attacks w ere weak, and approval could not be given on the basis of this test.
F r u it tre e re d sp id e r m ites (Panonychus u lm i)
In 1985 five experim ents w ere carried out with th ree replicates of three tre e s p er experim ental plot. T h e com pounds w ere applied according to their m ode o f action ju st before the hatching o f the w inter eggs, at 10% and at 80% hatching.
T he hatching o f the w inter eggs took place very late in two o f the experim ents, and fewer eggs th an expected were hatched. This is probably d ue to the stro n g and long winter.
Approved:
Plictran 80. w hich is a w ater soluble granule with the sam e active m atter
’cyhexatin’ as th a t of the already approved com pound Plictran 25. T he com pound has a knock-out longterm effect.
Nissorun 10 W P against the w inter eggs of the fruit tree red spider m ites at 10%
hatching w ith 0.6 k g /h a . A pplied on a mixed sum m er generation the com pound had a slower effect. T he active m atter is hexythiazox.
Apollo 50 SC against the w inter eggs of the fruit tree red spider m ites, applied at green cluster at the latest, with 0.4 1/ha. A pollo has the best effect w hen it is applied b e fo re th e em bryonic developm ent of the red spider m ites is too advanced. C onsequently it can be applied very early and m ay b e used as an alternative to o th er known com pounds against red spider mites.
Green apple a p h id s (A phis p o m i)
The sudden w arm w heather in July gave a unusually severe attack o f green apple aphids. A n experim ent was carried out on old trees, on young trees and on apple rootstock. T h e n u m b er of aphids was counted on m inim um 10 m arked shoots per plot before th e spraying.
A dim ethoat com pound, D L G D im ethoat 305, was approved as well as two pyrethroid com pounds, Sumicidin 10 FW and KVK Perm ethrin.
Leaf b liste r m ites
Due to the sudden occurrence of different species of leaf blister m ites in plums and pears in L olland a control experim ent was carried out with com pounds which were believed to have an effect against these pests. A t the sta rt of the experim ents only little was known about the biology of the leaf blister mites, particularly ab o u t w hen the leaf blister m ites leave their overw intering sites.
T herefore th e tim e for the first spraying was decided on the basis o f literature studies of experim ents m ade outside D enm ark. T h e first spraying on 29th A pril was carried o u t too early. Consequently a fu rth er spraying took place on 14th May.
The following com pounds w ere applied: T hiodan emuls., V ydate L, G usanthion M WP 25, M onsur and Lannate.
Against the p e a r leaf blister m ite (Phytoptus pyri) the effect was satisfactory, against the plum leaf m ite (Asculus fo c k e i), however, none o f the treatm ents were convincing.
b. Soft fru it, n u rse ry a n d glasshouse p lan ts (A. N ø h r R asm ussen)
In 1985 85 experim ents have been carried out in the above m entioned crops, com prising 25 different pests as well as grow th regulation and phytotoxic investigations. Som e o f the results achieved will be m entioned very briefly below.
G rey m ould (Botrytis cinerea) on straw berries
In 1983-85 6 experim ents have b een carried out to re-evaluate 8 approved com pounds. T he effect against grey m ould is m easured partly on the basis o f the nu m b er of diseased and healthy berries, partly on th e basis of the yield.
Vinclozolin and D ravifol had an effect against grey m ould o f 73%, thiram and tolylfluanid 61 and 65% respectively. F or the o ther 4 products, iprodion, captan, benom yl and thiophanatm ethyl, the effect obtained was betw een 31 and 46%.
T he above m entioned o rd e r o f products correlates with th e yields obtained. O n an average vinclozolin and D ravifol gave the best effect w ith a yield increase com pared to u n treated of about 55% . T hen followed thiram and tolylfluanid w ith 41% . T h e difference betw een these 2 figures is not certain, however. Iprodion, captan, benom yl and thiophanatm ethyl gave a very sim ilar effect, but the yield increase obtained w ith these products was only about 28% com pared to untreated.
L eaf sp o t (G loeosporidiella ribis) on black c u rra n ts
A re-evaluation of 8 approved products has been started in 1985. In general, th e effect was satisfactory, as m aneb, m ancozeb, captan and th iram provided an effect o f betw een 93 and 99% even for attacks in untreated of 96% .
T ithianon and dinocap + m ancozeb had an effect o f 83 and 73% , respectively. T h e effect o f benom yl and thiophanatm ethyl was below 30%, however.
2 products, which have not yet been m arketed in D enm ark, penconazol + captan and a new form ulation of dithianon, were also tested, and th eir effect was 99 and 91% , respectively.
A m erican gooseberry mildew (Sphaerotheca m ors-uvae) on b lack c u rra n ts
In 1985 experim ents w ere also started in which 5 approved products w ere com pared. F o r the best o f the products, fenarim ol and dinocap + mancozeb, th e effect was 69 and 62% respectively, whereas thiophanatm ethyl, benomyl and triadim efon gave an effect o f only 24, 16 and 10% respectively. 2 products, penconazol + captan and triadim enol, which have not yet b e e n m arketed, w ere also tested, and b o th had an effect sim ilar to that o f fenarim ol.
R ust (Phragntidium m u cron atu m ) on outdoor roses
In 1985 a series o f experim ents w ere started testing products against ru st in several nursery plants, e.g. roses. 8 products w ere tested. Oxycarboxin, triforin, benodanil, chlorothalonil, bitertanol and m epronil gave an effect of betw een 67 and 100%, w hereas the effect o f thiophanatm ethyl and penconazol was of 70 and 50%, respectively.
Infection by black spot (D iplocarpon rosae) was also seen. Only triforin, chlorothalonil an d b itertan o l provided sufficient effect against black spot.
Phytophthora in p o t plants
Control o f Phytoph thora in pot plants has been tested in each of the crops Peperom ia, S ain tpau lia and Raderm achera sinica. In the experim ents etridiazol 35%, etridiazol 70% , furalaxyl and fosetyl-AL w ere tested and com pared, mixed with the p o t soil and added to the w ater applied im m ediately after the potting.
In the experim ents artificial infection was applied by adding 10% infected soil to the pot soil.
Furalaxyl gave the best effect in all 3 experim ents and with both the two m ethods of treatm ent applied. T oo many plants died w hen etridiazol and fosetyl-AL w ere applied. T h e effect obtained was b e tte r for all the products when added to the water after th e potting than mixed with the pot soil.
Greenhouse re d sp id e r m ites (Tetranychus urticae) in straw berries
2 experim ents w ere m ade, where th e 1st spraying was carried out after the harvest. D icofol gave an effect of 100%, fenpropathrin of 99% , w hereas am itraz, tetradifon and hexythiazox gave effect of 93 and 97% . T he effect obtained w hen applying endosulfan and oxamyl was only 50-60%.
Straw berry m ites (Steneotarsonem us p a llid u s) in straw berries
2 experim ents have been m ade with control of straw berry m ites, w here the sprayings w ere carried out after the harvest. In one of the experim ents two sprayings w ere carried out with an interval o f 14 days, w hereas the o th er was sprayed only once.
The best effect, over 95% , was obtained with endosulfan. T hen followed am itraz and dicofol w ith an effect of 80-85%, w hereas fenpropathrin, tetradifon, hexythiazox and oxamyl had only little effect.
2 sprayings increased the effect very little com pared to 1 spraying.
T h rip s (Franklinelia p a llid ä ) on Saintpaulia
C ontrol o f thrips in pot plants usually causes no problem s, b u t in 1985 a few attacks of thrips w ere seen in Saintpaulia, which proved difficult to control. T h e species has not been finally determ ined, but it is supposed to be Franklinella p a llid a , a species, which habits flowers. From H olland it has been reported th a t the best com pound against these thrips is parathion, even though the effect w as insufficient.
In a cooperation w ith the Zoology D epartm ent 2 experim ents w ere m ade, w h ere only 1 spraying was carried out. T h e effect obtained with p arathion was approx.
60% , w hereas the effect obtained with 3 pyrethroids, cyfluthrin, fenpropathrin and alpham ethrin was 81, 74 and 65% , respectively, com pared to untreated.
c. Reduced ap p lic a tio n of pesticides in fru it trees a n d bushes bv changing dosages and time of sp ra y in g (Steen Lvkke Nielsen)
Project initiated by th e Jo in t C om m ittee for A gricultural R esearch and experim ents Black c u rra n t gall m ites
The m igration o f the gall m ites started by the end o f A pril and end ed in the beginning of A ugust.
Several com pounds w ere tested against the gall mites. E ndosulfan, oxamyl, methomyl and sulphur-thiram gave the best effect.
T reatm ent at different tim es showed that the best effect is obtained w ith 3 sprayings: at th e beginning of the flowering period, at the end of th e flowering period and 10-14 days later.
T reatm ent w ith spray volum es of from 100 to 1200 1 per h a showed th a t the best effect was o b tain ed with 400 1 per ha o r higher quantities. T he lowest volum es gave a p o o rer effect. T he spray technical experim ents in which a florescent colouring m a tte r was used showed an insufficient deposition on the leaves and the axillary b u d s at th e low volumes.
Gassing of black cu rran t cuttings infested with gall m ites was tried, using sulfotep and cyanogas. N o effect was obtained.
American g ooseberry mildew
Spraying with volum es from 200 to 1200 1 p er ha gave no differences in the effect for the higher volum es, but the effect obtained with 200 1 per ha was poorer.
The spray technical experim ents showed that the p o o rer effect obtained w ith 200 1 per ha was d ue to insufficient deposition particularly on the undersides of the leaves.
W hite-Pine b lis te r r u s t
Spraying w ith volum es from 200 to 1200 1 p er ha and with 2 dosages of triadim efon show ed that the best effect was obtained with 400 1 p er h a or higher volumes. 2001 p e r h a gave a poorer effect.
The lowest dose, which was 75% of the approved dose, gave as good an effect as the approved full dose.
Apple
D ue to technical difficulties with the equipm ent several spray technical experim ents w ere unsuccessful.
Apple scab
N o attacks of apple scab w ere found.
S praying of dewy leaves
T he deposit of pesticide on the apple leaves was doubled when spraying was carried out on dry foliage in the daytime com pared to spraying on dewy foliage in the m orning. T he quantity o f liquid applied was 200 1 per ha.
F ru it tree red sp id e r m ites
V olum es of 200 and 400 1 p er ha were applied with high an d low fluid pressure.
All treatm en ts gave 100% effect.
P e a r leaf b liste r m ites
Several com pounds w ere applied against the pear leaf b lister mites. Spraying at the end of A pril gave no effect. Spraying by m id M ay gave good effect.
Endosulfan, oxamyl, m ethom yl and carrbaryl gave good effect.
Plum gall m ites
A n experim ent was carried out similar to that perfo rm ed on pear leaf b lister mites, but the gall m ites disappeared all by themselves.
Blossom wilt on cherries
Several com pounds w ere tested against blossom wilt in ’K elleris 16’. Two quantities of liquid w ere used: 200 and 400 1 p er ha. T here was no difference in the effect of the two quantities. Irodion, thiophanat and p en co n azo l/cap tan had the b est effect against blossom wilt.