ON THE SUSCEPTIBILITY OF THE DIFFERENT VARIETIES
OF BIG-LEAFED TURNIP TO DAMAGE CAUSED BY

CABBAGE MAGGOTS (i Hylemyia spp.)

Anna-Liisa Varis

Department of Pest Investigation, Agricultural Research Centre,
Tikkurila

Received October 15th 1958.

The cabbage root fly ( Hylemyia hrassicae Bouche) and the turnip root fly
(Hylemyia floralis Fall.) are the most important pests occuring in the crucifers in
Finland. The larvae live in the underground parts of the plants burrowing channels
in them and often causing considerable losses in yield. The abundance and severity
of damage varies in different years, as well as in different species and varieties.

According to inquiries instituted in Sweden (1), the early varieties of the turnip
were attacked more severely than the late ones, likewise the round ones more
than the long ones. According to Morison (2), the hard varieties of the turnip and
swede became less damaged than the soft ones. This is due to the ability of the
former better to resist the aftereffect of affect, for the calculations done on the
amounts of the pupae on the surface of the hard and the soft varieties have shown
that the numbers are approximately equal. Reichelt (3) has on the basis of his
investigations on red cabbage, concluded that susceptibility is not a characteristic
of any specific variety, for although the distinct differences between the different
varieties can be noted in a year their order varies to a notable degree in different
years. Salonen (4) states that according to his observations at Inari (lat. 69°5’ N)
the roundish big-leafed turnips with dense foliage are distinctly more resistent
against damage caused by the cabbage maggots than the flatround ones, as the
root of the first is stouter and more amply branching. The larvae can easily cut
through the thin root of the flat-round turnip and the plant withers.

In the years 1951—1955 the damage caused by the cabbage maggots to the
different varieties of big-leafed turnip ( Brassica rapa L. v. rapifera Metzg.) was
studied at Tikkurila (lat. 60°20' N and long. 25°30' E). The examinations were
made on the varieties used in the field tests at the Agricultural Research Centre,
Department of Plant Husbandry. A total of 200 turnips of each variety was examin-
ed. The varieties used in tests for several years will be examined first. The following
varieties of big-leafed turnip were in general cultivation:
1. the so called »Native» big-leafed turnip, purple topped, strap-leaved, and flat, from Holland (A, R.

Zwaan & Sohn, Voorburg), the seed of the variety is cultivated in Finland.
2. the White Dutch, strap-leaved and flat, from the same firm as the former.
3. the Green Globe, green topped, roundish and lobate from England (Charles Sharpe & Co., Sleaford).



272

The damage suffered by these varieties during 1951—1955 is presented in
Table 1. The number of damaged roots is given in percentages. The average extent
of damage is also mentioned.

The damage varied considerably in different varieties during different years.
For that reason no conclusions on the susceptibility of a variety to damage could
be drawn on the basis of results of examinations obtained in one single year. The
»Native» big-leafed turnip became damaged most severely in the years of investig-
ation (the percentage of damage was 89 while the average of damage of all varieties
was 80). For a period of two years the variety Sirius tetrapl. Svalöv was included
in the test. This variety suffered distinctly slighter damage than the other varieties
mentioned above (in 1954 the percentage of damage was 82 and the average of
damage 1.6, in 1955 the corresponding numbers were 65 and 0.9).

In the second variety test, in which the »Native» big-leafed turnip also was
used as the standard, the following varieties were included in 1952—1955:

1. the »Native* big-leafed turnip.
2. Sirius Riesen, green-topped, round and lobate, from Holland (A. R. Zwaan & Sohn, Voorburg).
3. Zwaans Brabo, purple-topped, fairly long, and strap-leaved, from the same firm as No. 2.
4. Zwaans Favoriet, purple-topped, fairly long, and lobate, from the same firm as the above.
5. Gelria, purple-topped, fairly long, and strap-leaved, from Holland (N. V. Sluis en Groot’s, Enk-

huizen).
6. Lincolnshire Red Globe, purple-topped, long-round, and lobate, from England (Hurst & Son Ltd.,

London).
7. Purple Top Mammoth, form and origin as No. 6.

The damage to these species in different years is presented in Table 1.

Table 1. Damage caused by cabbage maggots (Hyletnyia spp) to the different varieties of the big-leafed
turnip at Tikkurila in the years 1951—55. Scale: 0 = fully healthy, 5 = fully damaged.

1951 1952 1953 1954 1955 Average
V ariety q <u cb q cb cb

öü cb uo cb uo q cb ud cb uo cbrt bjnrt ößcö bßrt tr cC öc G br
'S <4 *J rt-s rt-S rt-a «1 'S dG tnS I* G C. G Ci G S M SCb cb Cb Cb Cb CbCb CbCb Cb Cb Cbo > o >o > Cb > u > p>

Cb < Cb *Ccb < ö Cb •< Cb <!
tu pi, Dh (u eu cu

»Native* 80 1.0 89 1.8 82 1.3 99 1.9 96 1.8 89 1.6
White Dutch 57 0.8 78 1.5 78 1.2 91 1.9 82 1.2 77 1.3
Green Globe 51 0.6 80 1.6 62 1.0 93 2.4 91 1.5 75 1.4
Average 63 0.8 82 1.6 74 1.2 94 2.1 90 1.5 80 1.4

»Native» 77 1.6 87 1.3 96 1.8 94 1.8 89 1.6
Sirius Riesen 76 2.0 71 1.2 95 2.0 81 1.3 81 1.6
Zwaans Brabo 66 1.0 55 1.0 92 1.9 71 1.1 71 1.3
Zwaans Favoriet 86 1.1 60 1.2 92 2.1 83 1.3 80 1.4
Gelria 67 1.5 58 1.0 92 2.0 75 1.4 73 1.5
Lincolnsh. Red Globe 82 2.0 65 1.2 93 2.2 85 1.6 81 1.8
Purple Top Mammoth 91 2.3 75 1.4 96 2.2 85 1.7 87 1.9
Average 78 1.6 67 1.2 94 2.0 82 1.5 80 1.6



273

Variety 3 was damaged less than the others, the damage remaining below the
average each year. Variety 7 shows the opposite tendency the damage being con-
tinually above the average. The number of damaged specimens of the »Native»
big-leafed turnip was above the average in this group.

As the tests comprised turnips of different shapes, it is interesting to examine
whether the shape of a turnip has any relation to the damage caused by the cabbage
maggots. The material in this examination was considerably larger than that
mentioned above, because also varieties used in tests for shorter periods were
included. Since the tests did not comprise a sufficient number of turnips of each
shape in all the years in question, the results are presented in two different groups
(Table 2) in order to facilitate comparison. The total of 200 turnips of each test
member was examined also here. In cases where the tests of the same year had
the same sowing time and growing place or where the damage to the standards
was equal in extent, the results of the trials have been combined. The varieties
Sirius tetrapl. Svalöv and Petrovski Turnip have been excluded, because the damage
to these varieties very distinctly deviates from the general level.

The flat and flat-round big-leafed turnips were examined in the course of two
years and the damage was identical with that to the round big-leafed turnips in
the same tests. Likewise the damage in the round big-leafed turnips included in
the tests during five years was indentical with that in the long-round and fairly
long turnips in the same tests.

Table 2. Damage caused by cabbage maggots (Hylemyia spp.) to big-leafed turnips of different shapes
at Tikkurila in 1951—55. Scale: 0 = fully healthy, 5 = fully damaged.

The flat and flat-round The round The long-round and fairly long
Number Percentage Average Number Percentage Average Number Percentage Average

of of damage of of damage of of damage
varie- varie- - varie-
ties ties ties

1951 5 61 0.8 6 56 0.7
« 6 39 0.5 4 45 0.6

1952 19 70 1.3 22 71 1.5

Average 57 0.9 57 0.9

1951 4 45 0.6 3 39 0.4
1952 22 71 1.5 11 78 1.6
1953 5 62 1.0 7 65 1.2
1954 4 93 2.1 5 93 2.1
1955 4 83 1.4 5 80 1.4

Average 71 1.3 71 1.3



274

These tests show that the shape of the turnip does not seem to affect the
susceptibility of the variety to damage caused by cabbage maggots; the damage
was either slight or moderate. It is, however, obvious that in case the damage is
severe the round and long-round varieties which generally have strong roots endure
damage better and recover from it more quickly than the flat and flat-round varieties
with thin roots. Thus the shape of the turnip may also be of importance in regard
to the top yield.

Summary

Of all the varieties most generally cultivated in Finland (the »Native» big-
leafed turnip, the White Dutch, and the Green Globe) the »Native» big-leafed turnip
proved to be the most susceptible to damage caused by cabbage maggots. The
damage suffered by the Sirius tetrapl. Svalöv variety included in the tests only
for two years, was considerably slighter than in other varieties.

In the second test in which the varieties listed on page 272 were included for
four successive years, the Zwaans Brabo was damaged least of all, the damage
being below the average in every year investigated. As to the Purple Top Mammoth
the damage was continually above the average. In this group, too, the number of
the damaged specimens of the »Native» big-leafed turnip was above the average.

The shape of the turnips (the material was grouped as follows: 1. the flat
and flat-round, 2. the round, and 3. the long-round and fairly long turnips) did
not seem to affect the extent of the damage caused by the cabbage maggots, not
at any rate when the level of damage was slight or moderate as in the cases investig-
ated. It is, however, obvious, that in cases of severe damage the round and long-
round varieties which generally have strong roots, endure damage better and
recover from it more quickly than the flat and flat-round varieties with their thin
roots.

REFERENCES:

(1) Lundblad, O. 1933. Kälflugorna. Stat. växtskyddsanst. med. 3: I—lo3.
(2) Morison, G. D. 1938. The Turnip Root Fly (Phorbia floralis Fallen) in Northern Scotland. Verh.

VII intern. Kongr. Ent., Berlin 1938, p. 2576—2584.
(3) Reichelt, K. 1930. Achtet auf die Kohlmade. Hannoversche land. u. forstw, Ztg 83: 394—395.

(Ref. Tomaszewski & Nitsche & Langenbuch 1934).
(4) Salonen, A. 1954. Ristikukkaisten tuholaisista ja niiden torjunnasta Tunturi-Lapin alueella.

Koet. ja käyt. 6: 22.
(5) Tomaszewski, W. & Nitsche, G. & Langenbuch, R. 1934. Die Bekämpfung der Kohlfliegen

Chorthophila brassicae Bche und Ch. floralis Fall. Arb. Phys. angew. Ent. 1: 229—242,
280—290.



275

SELOSTUS;

ERI NAATTINAURISKANTOJEN ALTTIUDESTA KAALIKÄRPÄSTOUKKIEN (Hylemyia spp.)
AIHEUTTAMALLE VIOITUKSELLE.

Anna-Liisa Varis

Tuhoeläintä!kimuslaitos, Tikkurila

Vuosina 1951—55 tutkittiin Tikkurilassa kaalikärpästen aiheuttamaa vioitusta eri naattinauris-
kannoissa. Eri vuosina vioitus vaihteli tuntuvasti eri kannoissa, minkä vuoksi yhden vuoden tarkastus-
tulosten perusteella ei voida tehdä johtopäätöksiä jonkin kannan alttiudesta kaalikärpäsvioitukselle.
Tässä esitettyinä vuosina oli maassamme yleisimmin viljellyistä naattinauriskannoista (»kotimainen»
naattinauris, Valkea hollantilainen ja Green Globe) »kotimainen» naattinauris alttein kaalikärpäsvioi-
tukselle. Kahtena vuonna kokeessa olleessa kannassa Sirius tetrapl. Svalöv vioitus oli tuntuvasti vähäi-
sempi kuin muissa kannoissa.

Toisessa kantakokeessa (kannat on lueteltu sivulla 272) vioittui vähiten Zwaans Brabo, jossa
vioitus jokaisena neljänä koevuonna jäi keskimääräistä vioitusta vähäisemmäksi. Kannassa Purple Top
Mammoth taas vioitus oli jatkuvasti keskimääräistä runsaampaa. Tässäkin ryhmässä oli »kotimaisessa»
naattinauriissa keskimääräistä enemmän vioittuneita.

Nauriiden muodolla (aineisto oli ryhmitelty seuraavasti: 1. litteät ja litteänpyöreät, 2. pyöreät
ja 3. pitkänpyöreät ja pitkähköt nauriit) ei näyttänyt olevan vaikutusta siihen, miten altis jokin kanta
on kaalikärpäsvioitukselle; vioitus oli lievää tai kohtalaista. On kuitenkin ilmeistä, että vioituksen
ollessa ankara pyöreät ja pitkänpyöreät kannat, jotka yleensä ovat voimakasjuurisia, kestävät vioitusta
paremmin ja toipuvat siitä nopeammin kuin ohutjuurisemmat litteät ja litteänpyöreät kannat. Täten
saattaa nauriiden muoto vaikuttaa myös naattisadon määrään.