HOW ARE WEEDS INTRODUCED AND HOW ARE THEY SPREAD?
1. By live stock, carried in the hair or fleece or carried by the feet; in some instances passing alive with the excrement.
2. By unground feed-stuff purchased.
3. By adhering to the insides of sacks where they were placed with grain.
4. In barnyard manure drawn from town.
5. In the packing of trees, crockery, baled hay and straw.
6. By wagons, sleighs, threshing machines.
7. Sometimes by plows, cultivators and harrows.
8. By railway trains passing through or near a farm.
9. By ballast of boats at wharves.
10. By wool-waste at factories.
11. By birds, squirrels, and mice.
12. By water of brooks, rivers, by washing rains and by irrigating ditches.
13. By the wind aided by little wings or down, or by drifting on the snow.
14. By dropping seeds to the ground from extending branches and repeating the process.
15. By creeping root-stocks, as June grass, quack-grass and toad-flax.
16. By piercing potatoes, carrots, etc., quack-grass, June grass, Bermuda grass are sometimes carried to other fields or farms where the tubers and roots are planted.
17. A farmer buys clover seeds or grass seeds that were grown in some state that never before grew seeds that went onto his farm and thus he may get some new weeds. Seeds of alfalfa or some other crop bring new kinds of weeds, especially those of dodder. As every kind of weed goes onto a farm to stay there it follows that as a country becomes older the greater the number of kinds of weeds. As a rule each farm is annually getting more sorts of weeds, and as each farmer is cultivating weeds, they are more freely distributed in every field and along every roadside and by exchanging they are carried to neighboring and distant farms.
A great many farmers buy and sow whatever the merchant offers them under the name mentioned. For example, the college has a sample of something called clover seed, sold by a dealer in this state. It contains about 40 per cent of narrow-leaved plantain.