ICS65.020.20  
 
Reference number
DRS 357 -1: 2020
© RSB 2020
  
 RWANDA 
STANDARD  DRS
357-1
First  edition
2020 -mm-dd
Silk cocoon production — Code of practice  
— Part 1: Mulberry leaves production  
   
DRS 357 -1: 2020  
©RSB 2020 - All rights reserved                  ii 
 In order to match with technological development and to keep continuous progress in industries, 
standards are subject to periodic review. Users shall ascertain that they are in possession of the latest 
edition  
 
 
 
 
 
 
 
 
© RSB2020  
All rights reserved. Unless  otherwise specified, no part of this publication may be reproduced or utilized 
in any form or by any means, electronic or mechanical, including photocopying and microfilm, without  
prior written permission from R SB. 
Requests for permission to reproduce thi s document should be addressed to : 
Rwanda Standards  Board  
P.O Box 7099 Kigali -Rwanda  
KK 15 Rd, 49  
Tel. +250 788303492  
Toll Free: 3250  
E-mail: info@rsb.gov.rw  
Website: www.rsb.gov.rw  
ePortal: www.portal.rsb.gov.rw  DRS 357 -1:2020  
iii                ©RSB 2020 - All rights reserved  
 Contents  Page 
Foreword  ................................ ................................ ................................ ................................ ...................... iv 
1 Scope  ................................ ................................ ................................ ................................ ................ 1 
2 Normative references  ................................ ................................ ................................ ....................... 1 
3 Terms and definitions  ................................ ................................ ................................ ...................... 1 
4 Cultivation of mulberry trees  ................................ ................................ ................................ ........... 1 
4.1 Natural conditions suitable for mulberry cultivation  ................................ ................................ ......1 
4.2 Treatment of acidic and basic soil  ................................ ................................ ................................ ...2 
4.3 Site Selection for mulberry field  ................................ ................................ ................................ ......2 
4.4 Propagation of mulberry trees  ................................ ................................ ................................ ......... 3 
4.4.1  Preparation of mulberry nursery  ................................ ................................ ................................ .....3 
4.4.2  Plantation of mulberry trees  ................................ ................................ ................................ ............ 5 
4.4.3  Pruning of mulberry trees  ................................ ................................ ................................ ................ 7 
4.4.4  Maintenance and fertilization of mulberry fields  ................................ ................................ ............. 7 
4.5 Leaf harvesting  and storage  ................................ ................................ ................................ ........... 7 
 DRS 357 -1: 2020  
©RSB 2020 - All rights reserved                  iv 
 Foreword  
Rwanda Standard sareprepared by Technical Committees and approved by R wanda Standards Board (RSB) 
Board  of Directors in  accordance with the procedures of RSB, in compliance with Annex 3 of the WTO/TBT 
agreement on the preparation, adoption and application of standards.  
The main task of technical committees is to prepare national standards.  Final Draft Rwand a Standards 
adopted by Technical committ ees are ratified  by me mbers of RSB Board of Director s for publication and 
gazettment as Rwanda Standards.  
DRS 357 -1 was prepared by Technical Committee RSB/TC 029, Textile and Leather Technology . 
In the preparation of this standard, reference was made to the following standard  (s): 
1) TAS 8201 -2012 Good practices for silk cocoon production  
2) Sericulture training manual for farmers in Rwanda  
The assistance de rived from the above source is hereby acknowledged with thanks.  
DRS 357 consists of the following parts, under the general title Introdu ctory element — Main element : 
 Part 1: Mulberry leaves production  
 Part 2: Mulberry silkworm rearing  
Part 3: Silk cocoons handling  
Committee membership  
The following organizations were represented on the Technical Committee on Textile and Leather Technology 
(RSB/TC 029) in the preparation of this standard.  
Ministry of Trade and Industry (MINICOM)  
University of Rwanda -College of Science and Technology (UR-CST)  
National Agricultural Export Development Board (NAEB)  
 Rwanda Inspectorate, Competition and Consumer Protection Authority (RICA)  
HeWorks Silk Rwanda Ltd  
Rene Pharmacy  DRS 357 -1:2020  
v                ©RSB 2020 - All rights reserved  
 UTEXRWA Ltd  
OXALIS Ltd  
LIXIL/SATO  
Rwanda Standards Board (RSB) – Secretariat  DRS 357 -1: 2020  
©RSB 2020 - All rights reserved                  vi 
 Introduction  
Sericulture is an agro -based sector, involving rearing silkworms to produce silkworm cocoons and raw silk by 
reeling cocoons. The major sericulture activities comprise of mulberry cultivation to feed the silkw orm larvae, 
silkworm rearing to pr oduce cocoons, reeling of cocoons to unwind the silk filament and silk processing and 
weaving to gain value added silk products.  
The growth and development of silkworm is greatly influenced by environmental conditions. The biolog ical as 
well as cocoon -related characters are influenced by ambient temperature, rearing seasons, quality mulberry 
leaf, and genetic constitution of silkworm strains. Different seasons affect the performance of Bombyx moriL . 
Silkworm rearing depends on the availability of mulberry l eaves. It is occasionally limited by the dry season, 
which is the time to avoid silk worm rearing because mulberry growing isretarded due to drought and 
exceeding high temperature gives rise to the retardation of silkworm growing.  DRS 357 -1: 2020  
1                ©RSB 2020 - All rights reserved  
 Silk cocoon production — Code of practice — Part 1: Mulberry leaves 
production  
1 Scope  
This Draft Rwanda Standard establishes guidance on activities of production of mulberry leaves intended to 
feed mulberry silkworms.  
2 Normative references  
There are no normative references in this document  
3 Terms and definitions  
For the purposes of this standard, the following terms a nd definitions apply  
3.1 
Silkworm  
silkworm is the larva or caterpillar of the Bombyx mori  moth  
4 Cultivation of mulberry trees  
4.1 Natural conditions suitable for mulberry cultivation  
Silkworm Bombyx mori  require highly nutritive mulberry leaves to achieve high quality cocoon production . The 
environmental conditions to be considered for good production of mulberry leaves are herewith specif ied in 
table 1.  
Table 1 - Environmental conditions for good producti on of mulberry leaves  
S/N Factor  Recommendation  
i.  Temperature  240C - 280Ca 
ii.  water  annual rainfall  1,000 –2,500mm  
water content in the soil  70-80% 
iii.  Sunlight  sunshine of 9 to13 hours a day  
iv.  Air quality  mulberry field should be located more than 
100 meters away from tobacco plantation, 
factory smokes and agriculture chemicals.  
v.  Elevation  1000 -2000 metres  
vi.  Plantation design vis -à-vis the 
land slope  Slope below 150 mulberry trees can be planted in rows along 
the contour   
©RSB 2020 - All rights reserved                  2 
 Slope of 15° to 30°  terraces in order to minimize soil and nutrient 
erosion  
vii.  Soil  Type  Sandy, sandy loam, loamy soil and Clay 
loamy  
Condition  deep, fertile, and well drained with good 
capacity of holding moisture  
pH 6.5 - 6.8 
a When the temperature goes above 280C, irrigation practices should be applied  
 
4.2 Treatment of acidic and basic soil  
The acidic soils can be improved by the application of lime and green manure while Saline and alkaline soils 
can be improved by application of gypsum, sulfur or green manure as per T able 2.  
Table  — 2The quantity of gypsum or lime to be applied in different cases to maintain the pH range  
Gypsum for alkaline soil  
 Lime for acidic soil  
pH range  Amount of gypsum, 
tonnes/ha  
 pH range  
 Type of soil  
 Lime,  tonnes/ha  
Plain  
 Hilly areas  
 
7.4 to 7.8  
 2.0 
 5.5 to 6.5  
 Sandy  1.25 
 2.5 
 
7.9 to 8.4  
 5.0 
 Sandy loamy  2.50 
 5.0 
8.5 to 9.0  
 9.0 
 Loamy  5.0 
 7.5 
 
9.1 and above  
 14.0 
 Clay loamy  7.5 8.75 
 
4.3 Site Selection for mulberry field  
The following factors should be observed:  
a) The mulberry field (s) should be in close proximity to the rearing house to minimize labour costs an d the 
risks of leaf withering during transport;  
b) On sloped landscapes soil conservation measures such as trenches and management of contour bunds 
must be don e well to prevent soil erosion; and  
c) Mulberry trees can be grown in saline, alkaline and acidic soils after suitably amending the soils a s per 
Table 2 . DRS 357 -1: 2020  
3                ©RSB 2020 - All rights reserved  4.4 Propagation of mulberry trees  
Mulberry plantation can be raised by planting hard wood cuttings directly in the field, or saplings from nursery 
beds. The following activities are carried out:  
4.4.1  Preparation of mulberry nursery  
4.4.1.1  Site s election  
To prepare nursery bed, place where there is source of water  should be selected . The soils must be free from 
pests and ha ve high water holding capacity. Preferably place under shade  is recommended as per Figure 2 . 
4.4.1.2  Establishment  of nursery bed  
 The soil should be dug w ith weeding and removing stones,  followed by the application of e nough humus, lime 
and fertilizers at the rat e requested according to the soil fertility; then a raised bed of 1.5 meter wide and 10 
cm high  is prepared  as per Figure 1.  The length of each bed may be  adjusted to 5 -10 meters, depending on 
the size of land.  
 
Figure 2: Selection of nursery bed  
4.4.1.3  Select ion and preparation of cuttings  
The following should be considered during the selection and preparation of cuttings:  
a) The cuttings are made from mature hard wood using 6 -8 months old branches as per Figure 1, after 
removing leaves ; 
b) top part of green and te nder branches should be removed;  
c) branches shoul d be free from disease and pest;  
d) cuttings of size 15 -20 cm length with 2 -3 healthy buds are to be prepared;  
 
©RSB 2020 - All rights reserved                  4 e) cuttings should be cut at 45° and the top e nd should be 2 cm away from bud;  
f) cutting should be prepare d without damaging  the bark or splitting the base;  
g) keep the cuttings in wet gunny cloth /bag, till it used for planting;  
Figure 1: Mother trees of 6 -8 months old  
4.4.1.4  Planting cuttings  
Cuttings should be planted in the bed exposing only one bud over soil surface with spacing of 20cm by 20cm. 
After planting, soil around the cutting should be pressed firmly to avoid entry of dry air.  
4.4.1.5  Maintenance of nursery bed for hard wood cuttings  
The maintenance of the nursery is done as follows:  
a) Regular irrigation   is n ecessary for rooting and growth of mulberry saplings;  
b) Weeds should be removed; and  
c) Fertilizer such as urea  may be applied after two months of planting to enhance  growth.  
DRS 357 -1: 2020  
5                ©RSB 2020 - All rights reserved   
Figure 3: Preparation of nursery bed and hard wood cuttings  
 
4.4.2  Plantation of mulberry trees  
4.4.2.1  Establishment of mulberry plantation  
To cultivate mulberry trees, the following points should be considered:  
a) The conditions of the field site should be investigated before planting regarding the location and soil 
fertility etc;  
b) The feeder  roads are needed for access to the field for  the cultivation and harvesting;  
c) Before  planting saplings, the soil should be ploughed deeply; make the surface soil flat; compost and 
fertilizers including lime are ap plied to improve soil fertility;  
d) At a place where water drains poor in the rainy season, a drainage plan should be worked out and outlets 
install ed; 
e) To facilitate silk worm rearing, the mulberry plot  for young silkworms is prepared separatel y from the 
ordinary plantation; and  
f) In the dry s eason, irrigation should be applied to allow mulberry grow continuously.  
4.4.2.2  Planting ditch and base fertilizer  
The planting ditch is prepared 50 cm deep and 40 cm wide. At the bottom of ditch, organic matters (a bout 
10,000 kg/ha) are put in 15 cm deep and cov er it with soil of 5 cm deep. During digging the soil, upper and 
lower parts of soils are piled up separately and the upper soil is put downside and the lower soil u pside when 
mulberry trees are planted.  
 
©RSB 2020 - All rights reserved                  6  
 
Figure 4: Preparation of planting ditch changing the position of soils  
4.4.2.3  Spacing of mulberry  plantation  
It is recommended to have the space of 1.5 meters between rows and 50 cm of distance between trees.  
4.4.2.4  Planting method of mulberry saplings  
4.4.3.4.1   Two pieces of bamboo or wood sticks of 60 cm long are s truck into the ground at both ends of 
the ridge. A piece of strong rope is marked to show the inter -tree space (e.g. 50 cm). This rope is tied to the 
piles and tightly stretched. The mulberry saplings are put in the ground, according to the guide on the ro pe, 
leaving their upper portion about 5 cm above the ground.  
4.4.3.4.2.  In case mulberry saplings are prepared, the ditch is prepared and the organic matters are 
applied as described above, and the sapling is planted in the ditch according to the guide of the mark on the 
rope. Then, the ditch is filled with the soil surrounding the sapling and trod down (Figure 5).  
 
Figure 5: Planting method of a mulberry sapling  
 
DRS 357 -1: 2020  
7                ©RSB 2020 - All rights reserved  
 4.4.3   Pruning of mulberry trees  
4.4.4.1  Pruning is done after four months of plantating  
4.4.4.2  When the old mulberry branches are cut off at the bottom, the new shoots sprout and grow, by which 
more fresh leaves are produced and it makes easy to harvest mulberry leaves. The proper number of 
branches per one mulberry tree is 8 -10 per trunk.  
4.4.4.3  Care should be taken to ensure that the stem does not split and the bark does not peel off during 
pruning to prevent infections by pathogens.  
4.4.4  Maintenance and fertilization of mulberry fields  
In order to produce good mulberry leaves in abundance, the field should be maintained in good condition by 
weeding, ploughing, preventing drought or moisture damage, and applying composts and chemical fertil izer to 
make the soil suitable for a good growth of mulberry.  
4.4.4.1  Weeding  
Grass grows thick in the rainy season and hi nders the growth of mulberry trees by absorbing nutrients and 
moisture from the soil. Therefore, weeding should be done in early stage by controlling grass before  budding.  
4.4.4.2  Ploughing  
Ploughi ng is to turn over the uppermo st soil while burying weeds and crops  remains to decay, and facilitate 
soil aeration to activate microorganism action and hasten the decomposition  of organic matter in the soil . 
4.4.4.3   Mulching  
Mulching consist s of spreading organic matter (rice straw, cut grass, stalk of sorghum, waste of sugarcan es, 
and maize stalk, etc, over the soil surface to prevent drought damage through ev aporation of soil moisture.  
4.4.4.4   Fertization  
Mulberry trees need three components namely nitrogen, phosphorus and potassium from organic or/and 
inorganic fertilizers  
4.2.6.4.1   On one hectare of mulberry garden   N: 230 kg, P 2O5: 150 kg, K 2O: 170 kg are recommended  
annually in three doses for medium fertile soils.  
4.2.6.4.2   Organic matters can fertilize soil effectively.  . It is  recommended to apply: annually 10,000 kg or  
more of compost per ha.  
4.5  Leaf harvesting  and storage  
a) Leaf harvesting should be done during the cool hours of the day such as early morning and late eveni ng;   
©RSB 2020 - All rights reserved                  8 
 b) Leaves harvested in the morning could be used for the afternoon and night feeding;  
c) Leav es harvested in the late afternoon for the morning feeding of the following day ; 
d) Harvested leaves should be transported in gunny bags or baskets made of plant straws ; 
e)  Leaf storage is done in a separate room or in a corner of specially designed veranda or wooden leaf 
chamber well ventilated and covered with gunny cloth Mulbe rry leaves for young silkworms;  
f) Leaves should be spread on shelves ; 
g) Periodic turning of lea ves is essential to avoid leaf fermentation and to vent out metabolic heat ; 
h)  Water sprinkled on leaves on hot days and cover with wet gunny bag ; 
NOTE   Low temperature and high humidity are critical in leaf preservation  
 
 DRS 357 -1: 2020  
9                ©RSB 2020 - All rights reserved  
  
 
 
 
 DRS 357 -1: 2020  
 
Price based on nnn pages  
©RSB 2020  - All rights reserved