moduel 5 weeds Flashcards
A newly sown crop is more likely to out-compete weeds if:
(A) planted as early as possible in spring;
(B) the sowing rate is kept as low as possible;
(C) the seed is drilled as deeply as possible;
(D) good amounts of fertiliser are applied;
E) all of the above.
(D) good amounts of fertiliser are applied;
An example of a perennial weed with a creeping root system is:
(A) couch; (B) Californian thistle; (C) clustered dock; (D) yarrow; (E) creeping buttercup.
(B) Californian thistle;
The weed nodding thistle:
(A) fixes nitrogen using rhizobia on its roots;
(B) mainly germinates in autumn after a drought;
(C) has seeds that seldom last longer than a year once buried deeply;
(D) usually flowers in the first spring after germinating;
(E) can regrow from any part of its root if cut up.
(B) mainly germinates in autumn after a drought;
Perennial weeds are most likely to be found in which of these five situations:
(A) well-established sheep pastures;
B) wheat crops;
(C) pea crops planted after maize crops;
(D) flower gardens;
(E) brassica crops planted in autumn.
(A) well-established sheep pastures;
An example of a summer annual weed is:
(A) redroot;
(B) winged thistle;
(C) nodding thistle;
(D) blackberry;
(E) sheep’s sorrel.
(A) redroot;
An example of a biennial weed is:
(A) water pepper;
(B) ragwort;
(C) Californian thistle;
(D) winged thistle;
(E) barley grass.
(B) ragwort;
The weed species most likely to regrow from old plants following cultivation is:
(A) water pepper;
(B) nodding thistle;
(C) Californian thistle;
(D) winged thistle;
(E) barley grass.
(C) Californian thistle;
An example of a perennial weed with a rhizome is:
(A) willow weed;
(B) twin cress;
(C) clustered dock;
(D) yarrow;
(E) creeping buttercup.
(D) yarrow;
Weeds can reduce animal production because livestock don’t like grazing under prickly thistles or poisonous plants which is known as reduced pasture ……………… Weeds can also exude chemicals into the soil that affect crop plants growing nearby, and this is known as ……………… In newly planted forests, weeds can cause issues because they cover the soil, preventing it from heating up during the day during winter and thus making the young trees more susceptible to damage from ………………
utilisation
allelopathy
frost
The names of three (3) weed species that are summer annuals are:
……fathen…., …redroot….. and …wireweed…..
The names of three (3) weed species that are biennials are:
…hemlock……., ……ragwort……….. and ……Scotch thistle..
Black nightshade atributes
Summer annual
Establishes mainly in mid-spring
Very little after mid-summer
If established in autumn, flowers immediately
Plants produce seeds quickly, then keep seeding till killed by frosts
Seed spread by birds
Best controlled as it germinates or as a seedling
Barley grass: atributes
Generally a winter annual
Establishes in autumn in soil left bare by drought, once moisture comes with rain
Vegetative grass over winter: provides useful fodder Seed-heads form in spring: can reduce production by hard grazing at they form
Spends summer as a seed: dispersed by sharp awns in wool, etc
Seeds quite short-lived, unlike black nightshade
Californian thistle:
Seedling is very poor competitor, so only generally establishes in new pastures
Early in life, forms creeping root system, and new plants can develop from these roots
Daughter stems initially use sugars from mother plant, then later become self-sufficient
Flowers in summer; plants are dioecious so cross-pollinate
In late autumn, foliage dies back and plant overwinters as roots; re-establishesin spring from roots
five problems caused by weeds in crops
competition
pest and diosease problems
minimise harvesting dificulties
improve crop quality
stop weed seed banks increasing
