Session 8 - Control of the spread of the GGB through timely harvesting of maize and post-harvest farm hygiene

Topic: Control of the Spread of the GGB Through Timely Harvesting of Maize and Post-Harvest Farm Hygiene
Duration: 2 hours
Objectives:

By the end of this session, the participants should:

(i) understand the advantages of timely harvesting of maize
ii) know how to tell that the maize is physiologically mature and ready for harvesting
iii) understand the elements and value of post-harvest farm hygiene
iv) be sufficiently motivated to practice or teach timely harvesting of maize and post-harvest farm hygiene.

Target Group:

- Subject Matter Specialists (SMS's)
- Technical Assistants (TA's)
- Local leaders
- Farmers

Training Materials:

i) About two green maize plants (sample 1)
ii) About two physiologically mature maize plants (sample 2)
iii) About two dry maize plants (sample 3)
iv) Some maize damaged by:

* fungi
* birds
* rats
* insects - particularly the GGB

v) BB with chalk and an eraser or FC with paper and felt pen
vi) moisture meter

NB:

While this session may be conducted in a classroom, making use of the above materials, a demonstration on nearby farms with maize of the three categories mentioned above, i.e. green maize, mature maize and over-mature maize would be the most effective way of conducting this session.

Process:

10 minutes

Introduction

a) Before showing the participants the three samples of maize, the trainer should ask them to explain the signs by which they may tell that maize is ripe, i.e. just ready for harvesting. The correct explanations given by participants should be recorded on the BB or FC and the incorrect ones should be discussed to ensure that participants understand the reasons why they are unsatisfactory.

b) The trainer should then show the participants the three samples of maize and ask them (participants) to indicate which sample contains ripe maize and the reasons why they think so. Any sign of ripe maize which had not been named and recorded earlier may now be added to the list.

c) The trainer should then emphasize the following characteristics of mature maize, i.e. maize which has just reached the stage of physiological maturity:

20 minutes

The Signs of Physiological Maturity

1) the stalk system turns yellow or brown;
2) cobs begin to droop on the stalk (in most hybrids)
3) maize is no longer good for roasting
4) nine out of every ten kernels shows a black layer.

d) The trainer should show the participants how to carry out the black layer test as follows:

Step 1

Go to the field and take a random sample of maize cobs.

Maize Field

X - stalks from which samples of maize cobs may be taken

Step 2

From each cob, pick samples of ten kernels at random.

Step 3

From each kernel, peel back the covering at the tip. If the colour is black in at least nine out of every ten kernels, the field is physiologically mature to be harvested. If seven to eight out of every ten kernels show a black layer, then the maize has about a week to reach maturity and if only five to six kernels show the black layer, the field may be about two weeks from physiological maturity.

e) The trainer should explain the fact that the black layer indicates that the cob has sealed off supply of nutrients to the kernel now that it has matured. The farmer should explain the significance of moisture content and its measurement.

20 minutes

Advantages of Timely Harvesting

f) The participants should be encouraged to discuss the advantages of timely harvesting. Each advantage should be written on the BB or FC. The following are some of the advantages:

1) saves losses due to:

i) rodents
ii) theft
iii) bad weather
iv) fungi (moulds)
v) storage insect pests which infest maize in the field, e.g. the GGB maize weevil, etc.
vi) wild animals

At this stage, the maize kernels damaged by the above agents should be shown to the participants.

NB:

The above losses can easily reach seven to nine out of every one hundred bags.

2) Timely harvesting of maize also enables:

i) easier, better, timelier preparation of land for the next crop;
ii) farmers to get another crop (new maize or beans) in some areas;
* *iii) the fresh stalks to be fed to livestock.

20 minutes

Elements of Good and Hygienic Harvesting Practices

g) The trainer should then lead a group discussion (by asking leading questions) of the elements of good and hygienic harvesting practices. The following should come out of the discussion:

i) The cobs should be harvested and transported carefully to avoid mechanical damage. Mechanical damage lowers the grade of the maize and makes it susceptible to attack by storage insect pests.

ii) The stalks should be cut down immediately and burnt or fed to livestock.

iii) The cobs should be dehusked and the husks should be either burnt or fed to livestock.

NB:

Points ii) and iii) above should be emphasized by calling upon the participants to recall what they learnt during the session on ecology of the GGB. It should be made clear that immediate destruction of the stalks and husks eliminates the possible hiding and breeding places of the GGB.

10 minutes

Question Time

h) The trainer should allow some time for questions from the participants, after which he/she should summarize by repeating briefly the following points:

20 minutes

Summary of Lesson

i) The four signs of physiologically mature maize;

ii) The advantages of timely harvesting;

iii) The need to handle maize cobs carefully in order to avoid mechanical damage and its attendant results.

iv) The need to dehusk maize cobs immediately and to destroy stalks from the farm in an effort to remove possible dwelling and breeding places for insect pests, particularly the GGB. The value of feeding husks and stalks to livestock should be emphasized.