24 



supplied with more than the normal amount of moisture during the 

 remainder of the month, as well as in September, the irrigated rows 

 showed the beneficial effects of the extra water they had received. 

 Within two weeks after being irrigated, even in the presence of 

 heavy showers which seemed to wet the ground thoroughly, the arti- 

 ficially watered rows began to show signs of being reinvigorated. 

 New shoots began to appear among the old stocks, and the branches 

 of the mature plants showed new activity by appearing green at the 

 tip of every branchlet. In marked contrast to the irrigated plat, the 

 unirrigated rows began to show the usual signs of closing the season's 

 growth by the gradual dying of the inner branches. With the Avan- 

 ing of September the brownish appearance was quite noticeable, while 

 the irrigated plants continued green. 



Upon closer examination it was discovered that the unirrigated 

 rows were affected with asparagus rust {Puccinia asparagi), while 

 the irrigated plants were entirely free from the disease. This was to 

 be expected, as observations recorded by a number of investigators 

 have shown that rust is most destructive in seasons and soils where 

 the plants suffer for moisture. On the other hand, any condition 

 producing too great an amount of moisture about the plants is inju- 

 rious to them, since the rust is likely to injure plants weakened by 

 excess of moisture as well as by too little. 



It is well known that asparagus requires a moist soil for its best 

 development; but the advice of recognized authorities has usually 

 been against late summer or early fall mulching to conserve the mois- 

 ture, as such treatment was believed to favor the appearance of the 

 rust. That the disease is not aggravated by irrigating in late summer 

 is thoroughly proved by the test just completed. A careful estimate 

 of the extent of the rust disease among the irrigated plants places it 

 at one-half of 1 per cent. An inspection of the unirrigated rows 

 showed that fully 90 per cent of the stems of the plants had died, 

 probably from the effects of the rust. 



In Plate II, figure 2, is shown the difference in size and appearance 

 of the irrigated asparagus plants and those not irrigated, the stalks 

 on the left being only average specimens in point of size and are free 

 from disease. The group of small plants on the right was not irri- 

 gated. They were not only small, but were badly affected with rust. 

 Plate III, figure 1, shows a near view of sections of some of the aspar- 

 agus stalks seen in Plate II, figure 2. Those on the left were small, 

 and the disease was very noticeable, as indicated by the blotches and 

 irregularities in the bark. The stalks on the right were irrigated, 

 and were large, clean, and healthy. 



When the soil is deficient in moisture, late summer application of 

 water to asparagus will invigorate it sufficiently to cause it to resist 

 rust and enable the root stalks to store up a surplus supply of food 

 materials that will enable them to push up the young edible shoots 

 quite early in the spring that will be botli vigorous and abundant. 



