An estimation of agrochemicals spray amount on vegetables in Japan
Tomonori Fujita, Masaki Kamiya and Chishio Sasaki
Independent administrative institution, Food and agricultural materials inspection center,
Agricultural chemicals inspection station
Abstract
Spray amount (especially, the minimum which is effective to pests) in vegetable fields were
estimated mainly for evaluation of exposure to operators. The spray amounts on 5 crops were measured
in 2 years. Consequently, when crop height or crop wall area (= row length×crop height) was over
1.7 m or 20 m2, respectively, the spray volume might be exceed registered upper limit (300 L/10a).
The information of spray volume of the tests which conducted in the past were collected. As a result,the spray volume tend to increase in a small scale experiment, in efficacy and phyto-toxycity tests.
Tests on residues in crops did not appropriate to estimate requiring spray amount because the amountmight be set following the registered range. In addition, efficacy of chlorothalonil against pumpkin
powdery mildew was evaluated in the field at 4 different concentrations and spray amounts with thesame active substance application rate. In conclusion, efficacy was the lowest in the smallest sprayvolume treatment. Judging from the mechanism of action, coverage of spraying may important factor
such as protective fungicides.
Keywords: agrochemical, fungicide, efficacy, phyto-toxicity, spray amount, residues in crops,
powdery mildew, chlorothalonil, mechanism of action, protective, systemicon the evaluation of bees4, 5). These evaluations

1. Introduction
Ministryofagriculture,

forestryandare urgent issue and amount of spraying against

fisheries (MAFF) introduced the 2 newevaluation

factors

intheprocess

crops is a critical factor.

ofNowadays, registered spray amount in Japan

agrochemicals registration, in 2019 . The firstis generally 60-150 L/10a on cereals, 100-300

one is the evaluation of agrochemicals exposure

L/10a on vegetables and 200-700 L/10a on fruits

against users. The other one is the evaluation oftrees. These ranges were determined fromadverse effects of agrochemicals on honeybees

common Japanese agricultural practices in(Apis spp.). In the United States, already started

1990s. The users may regulate spray amountthe evaluation of agrochemicals exposure to thebased on size, growth stage and cultural

1)

2)

operators . Similarly, in the European Union,

practices of target crops in the ranges of statedguidance document on plant protection products

above. However, recent common spray amounts

exposure to operators and others was publishedin Japanese fields are unclear. In particular, thein 20143). The guidance documents are available

minimum spray amount which has significant

29

effectiveness

to

pests

is

an

vegetables and (2) to investigate the minimum

important

information to evaluate exposure against theeffective spray amount against a disease.

users and honeybees. Though, it is expected that

2. Materials and methods

there are many difficulties to determine the2.1. Estimation of common spray amount on

effective minimum spray amount because many

vegetables in Japanfactors affect the spray amount and effectivenessThe spray amounts on some vegetables werein actual fields. There were a few studies on thequantified in the field of Food and Agriculturaleffective

Materials

minimumsprayamountofInspection

Center,Agricultural

agrochemicals. In the previous study, the impact

Chemicals Inspection Station (Kodaira city,onmachines

Tokyo, Japan), for 2 years (2019-2020). In the

difference was investigated in vine field in thefirst year, cucumber (Cucumis sativus, cv. ‘VR-

United States 6). Although, from the aspect of thenatsu-suzumi’, TAKII & Co., Ltd., Japan),registration of agrochemicals in Japan, case

eggplant (Solanum melongena, cv. ‘Togenashi-

studies of spray amount in Japan might be moresenryo-nigou’, TAKII & Co., Ltd., Japan) and

important than foreign data because cropokra (Abelmoschus esculentus, cv. ‘Early-five’,cultural practices are different in each country or

TAKII & Co., Ltd., Japan) were grown7). In theregion.

second year, eggplant (cv. ‘Chikuyou’, TAKII &theeffectivenessof spray

Main factors which affect spray amountCo., Ltd., Japan), sweet pepper (Capsicum

might be crop height and numbers of leaves (orannuum, cv. ‘Kyo-hikari’, TAKII & Co., Ltd.,

leave area). These factors are varied by variation

Japan) and tomato (Solanum lycopersicum, cv.

of crops, climate, cultural practices and/or other‘CF-puti-puyo’, WATANABE SEED Co., Ltd.,

conditions. Therefore, as a case study, the spray

Japan) were cultivated. All the crops were grownamountwere

until the harvest stage (Table 1). Five liters (5investigated in this report. In addition, tokg) of the water containing spreading agent

estimate the minimum effective spray amount,(Gramin S, Mitsui Chemicals Agro, Inc., Japan;

effectiveness of chlorothalonil (TPN) under adiluted in 0.1 mL/L water) was filled in acertain condition was evaluated.

battery-powered sprayer (MUS153D, Makita

againstsomevegetables

The aims of this study were (1) to

Corporation, Japan) and the spray nozzle with 3

determine a common spray amount on someheads (ring shape, NAGATA SEISAKUSYO
Co., Ltd., Japan) was applied.

30

Table. 1. Summary of the crops conditions in 2020.
Crop

TomatoEggplant

Growth
Stage

Crop

Row

Row

Numberheightwidth

length

of

(m)

(m)

(m)

crops/row

1.7

0.7

10.6

25

26, June

45

1.1

0.7

10.3

17

20, July

67

1.0

0.7

10.0

20*

20, July67

Beginning of
harvestBeginning of
harvest

Sweet

Middle ofpepperharvestDays

Date ofspraying

after
planting* In 1 row, 19 was planted because of the lacking.
In the first year, spraying was done with 5, 5

to check spraying heterogeneity. There was noand 4 replicates (operators), in cucumber,remarkable heterogeneity of the spraying by

eggplant and okra, respectively. In the second

visual observation.

year, spraying was done with 5, 3 and 3

2.2. Investigation of spray amount in test

replicates (operators), in tomato, eggplant andresults

sweet pepper, respectively. In each spraying, an

The spray amounts in the test results which"adequate amount" of the water was sprayed,

were conducted in the past were investigated.

and in this report "adequate" means the water

The information were collected from the tests

amount dripping from leaves after spraying. The

for efficacy and phyto-toxicity and residues inspraying was done on the each rows and thecrops those of conducted in Japan. The

remaining water amount was measured. Theninvestigated crops were pumpkin (Cucurbita

the actual spray amount was calculated byspp.), sweet pepper and tomato (these crops

subtracting the remaining water volume from thewere the same as served for the fieldinitial water volume. After that, based on theexperiments in 2020). The results from 2013 towidth and length of the fields, spray amount on

2019, and the results from 1970 to 2015 were

the fields were estimated. The unit of spraying

collected on the test of efficacy and phyto-amount for a certain area is expressed with

toxicity, and on the test of residues in crops,"L/10a", following Japanese agrochemicals

respectively, but in some year, tests on theseregistration system. In addition, the crop in a row

crops were not conducted. The crops formerly

was regarded as a wall and the areas of the wall

surveyed7) were not researched again.

(crop wall area; CWA) was calculated by the

2.3. Estimation of the minimum effective

length of row and each crop height. Pieces ofspray amount against pumpkin powdery

Water sensitive paper (TeejetⓇ

Technologies,

mildew

the United States) were placed on 2 to 3 points

The effect of chlorothalonil (TPN) inin each rows with 2 to 3 vertical position in orderdifferent spray amount with the same amount of31

a

Eventually, the amount of active substance in theformulation, ST Daconil 1000 (TPN 40.0%,

unit area was the same in all the treatments.

Sumitomo Chemical company, Ltd., Japan) was

Spraying was done by using a pressure sprayer

used. Pumpkin (cv. ‘Kuribou’, SAKATA SEED

(No. 4130, FURUPURA Co., Ltd., Japan) with

Corporation, Japan) were grown in concrete

1 L tank. Five hundred mili liter of the eachframes (0.7 × 0.7 m). Five treatments weredilution was filled in the sprayer and pressureestablished with 3 replicates in each and placed

was adjusted at ca. 330 kPa. The spraying rate offollowing randomized block design. Treatments

the sprayer was 4.08 mL/s (average of 3

were (1) 2000 fold dilution and 200 L/10a spray,measurements), thus the spraying time was(2) 1000 fold dilution and 100 L/10a spray, (3)determined as 24 seconds in treatment (1), 12

500 fold dilution and 50 L/10a spray, (4) 250

seconds in (2), 6 seconds in (3) and 3 seconds infold dilution and 25 L/10a spray, and (5)(4). The spraying was conducted twice at August

untreated control (Fig. 1). The treatment (2) is

5 and 12, 2020. The efficacy was evaluated 7

the registered minimum amount on pumpkin indays after the second treatment (19 August,Japan, and the amount of active substance per2020).

activesubstance

wasevaluated.

As

unit area was equivalent to 40.0 g/10a.
(2)-Ⅲ

(4)-Ⅱ

(1)-Ⅱ

C-Ⅲ

(4)-Ⅰ

(4)-Ⅲ

(2)-Ⅰ

C-Ⅱ

(3)-Ⅱ

(3)-Ⅰ

(3)-Ⅲ

(1)-Ⅲ

(1)-Ⅰ

2-Ⅱ

C-Ⅰ

Fig. 1. The layout of the experimental plots. The roman numerals mean replicate number, numbers inparenthesis mean each treatment and "C" means untreated control.

32

Powdery mildew (naturally occurred and theSpearman’s rank correlation coefficient was

species was unknown) was already occurred atdetermined. In the case of correlation was

the beginning of the experiment and diseased

observed, test of correlation was done (p = 0.05).

leaves were not removed. The effectiveness was

On the results of experiment 2.3, diseaseevaluated based on disease index (DI). The

severity was submitted for statistical analysis. At

index was determined based on the proportion of

first, to check normality of the data, the Shapiro-denoting area of symptoms on the leaves (0: No

Wilk test was done on the disease severity ofsymptoms, 1: less than 5%, 2: 5-25%, 3: 25-50%,

each treatment. As a result, all of the data wasand 4: more than 50%). Ten leaves (with disease

not normally distributed, therefore the Kruskal-

indices 0 or 1) were marked in each plots andWallis test was applied (p = 0.05). Whenobservation of progress of the disease wassignificance was detected in the Kruskal-Wallis

conducted on these leaves. Disease severity (%)

test, the Steel-Dwass test was employed (p =and disease suppression rate (DSR; %) was0.05).

calculated with the following equation.

3. Results and discussion

Disease severity (%) = Σ (Disease index × The

3.1. Estimation of common spray amount on

number of investigated leaves) / (The number

vegetables in Japanof investigated leaves × 4) × 100

3.1.1. Results of the spray amount on each

DSR (%) = 100 – (The disease severity in thecrops and the prediction of spray amountThe maximum, the minimum and thetreatments / The disease severity in the

average spray amounts are shown in Table 2.

untreated control) × 100

Cucumber, eggplant (in 20197)) and tomato

2.4. Statistical analysis
The free software R (ver. 4.0.3) was used forneeded the spray amounts above the registeredstatistical analysis.

range (100-300 L/10a; Fig. 2). On cucumber, 4

On the results of investigation 2.2, the dataof 5 operators sprayed more than 300 L/10a7),

containing crop height were extracted and the

however on tomato, only 2 of 5 operators

relationship between the height and the sprayexceeded for 300 L/10a. Based on this result,amount was analyzed. At first, normality of thecrop height of ca. 1.7 m with tomato-like shapedata was checked by the Shapiro-Wilk test. The

was considered to be the upper limit which canPearson correlation coefficient was calculated

be uniformly sprayed with the 300 L/10a spraywhen the data indicate normality, otherwise, thevolume.

33

Table 2. The maximum, the minimum and the average spray amounts on each crops.
Spray amount

Crop

Maximum

Minimum

AverageTomato372.3 L/10a

282.0 L/10a

310.1 L/10a

Eggplant

147.0 L/10a

105.1 L/10a

134.1 L/10a

Sweet pepper

167.7 L/10a

116.1 L/10a

139.7 L/10a

Even though, the spray amount for eggplant(and stems) were less in 2020 than in 2019 bywith 1.2 m height in 2019 was exceeded thevisual observation. Especially, the horizontal

7)

upper limit . The spray amounts on eggplantarea which stems were exiting seemed to be

was 314.6 L/10a in 20197) but 134.1 L/10a insmaller in 2020 than in 2019. Compared to the2020. Their heights were similar in these 2 years

conditions in 2019, it was decreased that the(1.2 m in 20197) and 1.1 m in 2020). The area ofnecessity to move the spray nozzle horizontally2

the field was larger for 0.9 m in 2020 than inin 2020, and this might lead the reduction of the20197) and this was from the length of rows

spray amount.

(+1.3 m). The decrease of the spray amount may

The spray amount for sweet pepper was

be caused by the difference of the number ofwithin registered range. The height of sweet

leaves. The number of leaves in all the field were

pepper was 1.0 m, and shorter than the other3760 (actually counted) and 3468 (estimatedcrops. Main stem of sweet pepper was along afrom a photo), thus the leaves was 292 (-7.8%)

pole and 2 lateral stems were pulled up withless in 2020 than in 2019. The difference of thewires thus stems grew vertically. These

number of leaves was not obvious, but operators

agricultural practices cause decrease of the

got the impression that the number of leaves

horizontal area to spray and the spray amount.

34

450

Spray amount (L/10a)

400
350
300
250
200
150
100
50
0
Cucumber

Eggplant

Eggplant(2019)(2020)

Okra

Sweet pepper

TomatoCrop (year)
Fig. 2. The spray amounts on each crops in 2 years experiments. Error bars indicate standard deviation,
upper line and bottom line means 300 L/10 and 100 L/10a, respectively (the range of spray amounts
in registration).
The spray amount can be predicted by crop

crops based on height and CWA. The number ofheight and crop wall area (CWA) in some cases.

leaves or total leaf area might be related to theBased on the obtained results, in the case of crop

spray amount on eggplant-like shape crops withheight is taller than 1.7 m (e.g. cucumber andhorizontally spread leaves. The spray amounts

tomato; Fig. 3) or CWA is over 20 m2 (e.g.

for eggplant were varied in 2019 and 2020, andcucumber; Fig. 4), the spray amount will

this may be caused by the difference of thepossibly exceed 300 L/10a.

number of leaves. This indicated that it is

Although the spray amount was more thaneffective to predict the spray amount by the

300 L/10a on eggplant in 2019, even the heightnumber of leaves or total leaf area for eggplant-

2like shape crops.

was 1.2 m and CWA was 10.8 m . Therefore, thespray amount may not be predictable for all the

35

450

Spray amount (L/10a)

400
350

Cucumber

300

Eggplant (2019)250

Eggplant (2020)

200

Okra

150

Sweet pepper
Tomato100

300L/10a50

Crop height (m)

0
0

0.5

1

1.5

2

Fig. 3. The relationship between crop height (m) and spray amount.
450

Spray amount (L/10a)

400
350

Cucumber

300

Eggplant (2019)250

Eggplant (2020)
Okra

200

Sweet pepper

150

Tomato100

300L/10a50

Crop wall area (m2)

0
0

5

10

15

20

25

Fig. 4. The relationship between crop wall area (CWA) and spray amount.
As a conclusion, in the case of crops grown

number of leaves or leaf area might be useful toin vertically using poles, nets or wires, crop

predict the spray amount. Inversely, when crops

height or CWA may be effective to predict theof which height is shorter than 1.6 m and leaves

spray amount. On the other hand, in the case ofare extending vertically, it is predicted that thecrops with horizontally spread stems, likespray amount unlikely to exceed 300 L/10a.

eggplant, crop height and CWA should not be

Further investigation is necessary to reveal theapplicable to predict spray amount but therelationship between the number of leaves (total

36

leaf area) and the spray amount.
3.2. Investigation of spray amount in testfor pumpkin, sweet pepper and tomato,

results

respectively. The maximum, the minimum and3.2.1. Tests on efficacy and phyto-toxicity

the average spray amounts on each crops areshown in Table 3.

The numbers of tests on efficacy and phytotoxicity for investigation were 149, 444 and 575,

Table 3. The numbers of tests, the maximum, the minimum and the average spray amounts on eachcrops from the tests on efficacy and phyto-toxicity.
Spray amountThe number of

Crop

tests

Maximum

Minimum

Average

Pumpkin

149

500 L/10a36.0 L/10a

185.4 L/10a

Sweet pepper

444

510 L/10a50 L/10a235.1 L/10a

Tomato575

500 L/10a55.6 L/10a

268.6 L/10a

The most frequently applied spray amount(Fig. 5). Based on the Spearman’s rank

range for pumpkin was 151-200 L/10a (Fig. 4).

coefficient correlation, a little coefficient was

Three of one hundred forty nine tests exceeded

observed and there was no significance (Fig. 8, r

300

= 0.28, p = 2.0×10-3).

L/10a.

The

results

containing

theinformation of crop height were extracted and

For the tests for tomato, 251-300 L/10athere was no normality of the data, thus thespraying range was the most frequently appeared

Spearman’s rank correlation coefficient was(Fig. 6). Judging from the average spray amount,determined from the test results of pumpkin. The

most of the tests for tomato were conductedweak

betweenbetween 100-300 L/10a range. Similarly withpumpkin height and spray amount, but thethe other crops, the Spearman’s rank correlation

correlation was not significant (Fig. 7, r = 0.46,

coefficient was determined. There was weakp = 2.0×10-5).

correlation between tomato height and spraycorrelation

wasobservedamount but the correlation was not significant

Among the tests for sweet pepper, the most(Fig. 9, r = 0.46, p = 2.8×10-11).

frequently sprayed volume was 251-300 L/10a

37

50
40
30
20
10
0

Number of tests
37

47

22

22

18

2

1

Spray amountFig. 4. The number of tests of pumpkin on efficacy and phyto-toxicity. The numbers above the graphs
indicate the number of tests which were conducted with the spray amount range written in the bottom.
250

Number of tests
193

200
150
83

100
50

7

107

18

17

19

0

Spray amountFig. 5. The number of tests of sweet pepper on efficacy and phyto-toxicity. The numbers above thegraphs indicate the number of tests which were conducted with the spray amount range written in thebottom.

38

300

Number of tests

260

250
200
146

150
85

100
50
0

33

36

13

2

Spray amountFig. 6. The number of tests of tomato on efficacy and phyto-toxicity. The numbers above the graphs
indicate the number of tests which were conducted with the spray amount range written in the bottom.
350

Spray amount (L/10a)

300
250
200
150

y = 25.896x + 155.14
R² = 0.1739

100
50

Crop height(m)

0
0

0.5

1

1.5

2

2.5

3

Fig. 7. The relationship between crop height and spray amount on pumpkin.

39

3.5

600

Spray amount (L/10a)

500
400
300
200
y = 38.661x + 214.67
R² = 0.0472

100

Crop height(m)

0
0

0.2

0.4

0.6

0.8

1

1.2

1.4

1.6

1.8

2

Fig. 8. The relationship between crop height and spray amount on sweet pepper.
450

Spray amount (L/10a)

400
350
300
250
200
150

y = 53.628x + 183.5
R² = 0.2182

100
50

Crop height (m)

0
0

0.5

1

1.5

2

2.5

Fig. 9. The relationship between crop height and spray amount on tomato.
In most cases, spray amounts for the tests on

caused by such as heterogeneity of spraying,efficacy and phyto-toxicity presumed to bepossibly investigator may apply much moredetermined by crop size (e.g. height) but thereamount of agrochemicals dilution than thewas no significant correlation between crop

required minimum amount. Therefore, it washeight and the spray amount in this survey. One

difficult to determine the minimum sprayof the main purpose of these tests is to confirm

amount based on the data from efficacy andeffectiveness of the novel agrochemicals thus

phyto-toxicity test.

spray amounts may set more than the required

Possible causes were explored why moreminimum amount. To avoid the test failure

than 300 L/10a of spray amount was needed in40some of the examinations. Firstly, on tomato, it

were done in the smallest area but the sprayis tend to increase the spray amount in the case

volume was the largest among the tests whichof the small experimental plot area (less than 7

experimental areas were stated. In general, it

m2, Fig. 12). Especially, equivalent to 500 L/10a

may be more difficult to spray in small area

water volume was sprayed in the 2 tests

uniformly than in large area because of decline

conducted in 1.5 m2 plots. These experimentsof the total liquid volume.

600

Spray amount (L/10a)

500
400
300
200
100
Area of plot (m2)

0
0

10

20

30

40

50

60

Fig. 10. The relationship between the area of plots and the spray amounts of pumpkin on the efficacy
and phyto-toxicity tests.

600

Spray amount (L/10a)

500
400
300
200
100

Area of plot (m2)
0
0

5

10

15

20

25

Fig. 11. The relationship between the area of plots and the spray amounts of sweet pepper on theefficacy and phyto-toxicity tests.

41

Spray amount (L/10a)

600
500
400
300
200
100

Area of plot (m2)

0
0

10

20

30

40

50

60

Fig. 12. The relationship between the area of plots and the spray amounts of tomato on efficacy andphyto-toxicity tests.
The battery-powered sprayer which used in

the

tests

on

pumpkin,theminimum

our experiment ejects ca. 580 mL/min. As anexperimental area was 4.5 m2 and relatively

example, in the case to spray 3 L water in 10 m2

larger than tomato (1.5 m2) and sweat pepper

by using this sprayer, required spraying time is(2.7 m2). Thus, the experimental area was notabout 5.2 minutes. This time is considered

considered as a main factor of the increase of theenough to spray for all of the examination area

spray amount on the tests of pumpkin. The

uniformly. However, in the case to spray 0.3 L

reason of the increase of the spray volume inwater in 1 m2, required spraying time is about 31

pumpkin was still unclear.

seconds. It may difficult to spray uniformly in a

3.2.2. Tests of residues in crops

small plot using common battery- or gasoline-

The numbers of tests of residues in crops are

powered sprayer. To prevent heterogeneity ofshown in Fig. 13〜15, and the maximum, thespraying, it is required to increase the total

minimum and the average spray amounts are

spraying volume and this might be the mainstated in Table 4. As a result, 1 of 149 tests

cause of the excess spraying. When the test is

exceeded 300 L/10a in pumpkin. Similarly, 1 of

conducted in small experimental area, specific

217 tests and 8 of 370 tests applied more thansprayer (e.g. small amount spraying applicable)

the upper limit in sweet pepper and tomato,or some other techniques may be necessary.

respectively. In these tests, only a few of themAmong the tests on sweet pepper, thestated crop height thus the relationship between

2minimum experimental area was 2.7 m .

the height and the spray volume could not be

Similarly to the tests of tomato, a main factor ofevaluated. All of the tests exceeding 300 L/10a

the increase of the spray amount may be the area

were conducted before 2003, and the differenceof experimental plots. On the other hand, amongof the test rules between the past and the present

42must be the main factor of the increase of thetheregistration

range(100-300

L/10a).

spray volume.

Therefore, it may be not effective to refer thesetests to determine spray amounts on each crops.

It was indicated that the spray amount intests of residues in crops may be set following
100

Number of tests
80

80

64

60
34

40
22
20
2

0

0

1

Spray amountFig. 13. The number of tests of pumpkin on residues in crops. The numbers above the graphs indicate
the number of tests which were conducted with the spray amount range written in the bottom.
120
100

Number of tests

113

80
49

60

41

40
20

2

13
0

1

0

Spray amountFig. 14. The number of tests of sweet pepper on residues in crops. The numbers above the graphs
indicate the number of tests which were conducted with the spray amount range written in the bottom.

43

160
140
120
100
80
60
40
20
0

143

Number of tests
120

0

95

6

3

5

Spray amountFig. 15. The number of tests of tomato on residues in crops. The numbers above the graphs indicate
the number of tests which were conducted with the spray amount range written in the bottom.
Table 4. The numbers of tests, the maximum, the minimum and the average spray amounts on eachcrops from the tests on residues in crops.
Crop

Spray amountThe numberof tests

Maximum

Minimum

Average

Pumpkin203

400 L/10a50 L/10a229.6 L/10a

Sweet pepper

219

400 L/10a70 L/10a224.0 L/10a

Tomato372

500 L/10a144 L/10a251.2 L/10a

3.3. Estimation of the minimum effective(2) and (3), but lowered in (4). Significant

spray amount against pumpkin powdery

difference was observed by the Kruskal-Wallis

mildew

test among the treatments (p = 0.046) however
there was no significance by the Steel-Dwass

The result is shown in Table5. In thetest (p > 0.05, among all the treatments).

untreated control, the average of DI was 4. The
suppression rate was similar in the treatment (1),44

Table 5. The result of the experiment on the effect of TPN against pumpkin powdery mildew (Theevaluation of effectiveness was conducted in 7 days after the second treatment).
The number
Treatment

Replicate

Disease index

Disease

Diseaseofinvestigated

0 1 2 3 4

Severity (%)

suppression rate

leavesTreatment (1)×2000
200 L/10aⅠ

10 5 3 2 0 0

17.5

Ⅱ

10 5 5 0 0 0

12.5

Ⅲ

10 2 6 2 0 0

25.0

Average
Treatment (2)×1000
100 L/10a18.3

Ⅰ

10 0 6 4 0 0

35.0

Ⅱ

10 2 8 0 0 0

20.0

Ⅲ

10 4 6 0 0 0

15.0

Average
Treatment (3)×500
50 L/10a23.3

Ⅰ

10 3 6 1 0 0

20.0

Ⅱ

10 2 6 2 0 0

25.0

Ⅲ

10 5 5 0 0 0

12.5

Average
Treatment (4)×250
25 L/10a19.2

Ⅰ

10 1 6 3 0 0

30.0

Ⅱ

10 3 4 3 0 0

25.0

Ⅲ

10 0 9 0 1 0

30.0

Average

28.3

Ⅰ

10 0 0 5 4 1

65.0

UntreatedⅡ

10 0 0 2 3 5

82.5

controlⅢ

10 0 6 3 1 0

40.0

Average(DSR, %)

70.3

64.9

68.9

54.1

61.7 －

substance

affected effectiveness. In addition, in theamounts in each plots were the same, DSR was

treatment (1), the concentration of the dilution

lower in the treatment (4) by 10.8 points

was half against the approval application method

compared to the treatment (2), i.e. the approved

but the efficacy was almost the same level as theapplication method. This means the spray

treatment (2). Therefore, coverage of spray may

volume, more specifically, coverage of spraybe more important on the effectiveness of TPN

Thoughtheappliedactive45

than concentration. Based on this result, at least

Specifically, protective fungicides or spiracle-

50 L/10a spraying proportion may be required

blocking insecticides may require relatively

for a certain control level, in the tested

much amount of the spraying. In contrast,

conditions. Although, it should be noted that this

agrochemicals with systemic action can beexperiment conducted in exceedingly small area

effective at the low application rate. Further

thus reliability is much lower than common

study is necessary to evaluate the effectivenesseffectiveness tests.

of each active substances at different level ofWise et al. (2010)6) studied on the impact ofspray volume.

sprayer type and spray volume against efficacy

Referencesof 2 fungicides (ziram and azoxystrobin) in the1) Ministry of agriculture, forestry and fisheries:

United States vine field. According to this report,Dataspray volume of the airblast sprayer significantly

agricultural chemicals. (2020). (in Japanese)

affected fungicide performance against foliar

2) United States Environmental protection

powdery mildew of vine (Vitis labrusca) with

Agency: Series 875 – Occupational and

468 L/ha (high water volume) being better than

Residential

187 L/ha (low water volume). This was most

(1996).

6)requirementsfor

Exposureregistration

Test

of

Guidelines.

apparent in the case of ziram . The effectiveness3) European Food Safety Authority: Guidanceof azoxystrobin with 187 L/ha and 468 L/ha didon the assessment of exposure of operators,

not show significant difference. Ziram isworkers, residents and bystanders in risk

protective

assessment for plant protection products.

fungicidebut

azoxystrobin

is(2014).

systemic fungicide. This result indicates thespray amount is important factor especially in4) European Food Safety Authority: Guidanceprotective fungicide. Additionally, in the aboveon the risk assessment of plant protection

study, the type of fungicide affected diseaseproducts on bees (Apis mellifera, Bombus

6)

spp. and solitary bees). (2013).

control more than did water volume, in general .
In this study, TPN was applied to pumpkin5) United States Environmental protection

powdery mildew, and TPN is protective

Agency: Series 850 – Ecological Effects Test

fungicide8). In the previous study6), the amounts

Guidelines – 850.3020 – Honey Bee Acuteof active substance were different among theContact Toxicity and 850 – 3030 – Honey

treatments. Whereas in this study, the amounts

Bee Toxicity of Residues on Foliage. (2012).

of active substance in each treatments were the6) J. C. Wise, P. E. Jenkins, A. M. C. Schilder, C.

same but the effectiveness was weaken in the

Vandervoort, R. Isaacs: Spray type and water

least spray volume treatment. As a conclusion,

volume influence pesticide deposition andmechanism of action should be included incontrol of insect pests and diseases in juice

consideration to establish proper application

grapes. Crop Prot. 29, 378-385 (2010).

method as well as dilution rate or spray volume.

7) M. Kamiya, T. Fujita, C. Sasaki: Investigation46

of the reality of the agrochemicals sprayamount in Japan. Res. Rep. Agric. Chem. 12,
6-11 (2020) (in Japanese).
8) Japan Plant Protection Association: 14 TPN〔Chlorothalonil〕. In "Nouyaku Handbook."
Ed. By Japan Plant Protection Association,
Jyohoku-insatsu-syo, Tokyo, pp. 499-501,(2016) (in Japanese).

日本における農薬の散布液量実態調査
藤田智紀，神谷昌希，佐々木千潮
独)農林水産消費安全技術センター
摘要
農薬使用者への曝露評価に資することを主な目的として，野菜類に対する散布液量を推定した．特に，病害虫に対して効果を得られる最小量に着目した．2 か年で 5 作物に対する散布液量を評価した．この結果，作物の草丈が 1.7 m を超える場合や，畝の長さと草丈を乗算して求められる散布壁面積が 20 m2 を超えるような場合に，登録上の上限値である 300 L/10a を超える散布液量を要することが示唆された．また，過去に実施された薬効・薬害試験及び作物残留試験における散布液量の情報収集を行った．この結果．薬効・薬害試験においては，小面積で実施された試験では散布液量が増加する傾向がみられた．作物残留試験では，登録上の使用液量を前提として散布液量が設定されていると思われ，散布液の必要量を推定する資料とするには不適であると考えられた．さらに，かぼちゃのうどんこ病を対象として，クロロタロニル(TPN)の効果を評価した．異なる 4 段階の希釈液を調製し，有効成分投下量が全ての処理区で同等となるよう散布を実施した．この結果，散布液量を最小とした処理区(250 倍液，25 L/10a 相当を散布)において，最も効
果が低かった．保護殺菌剤のような作用性をもつ農薬においては，散布液の付着範囲は効果に影響を及ぼすことが示唆された．

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