Show Cov Cover r r Cro Crops p Lower sLower Temperature Tern n ei e Some G b Tests Show Frost Hazard Is Increased Slightly 01 Pr Prepared pared by the United United uro States Dell Department r of Agriculture The weather bureau of th the United States Department of at AgrI Agriculture has conducted several experiments In cit cit cit- growing rus-growing sections of ot California to tor determine what influence a cover crop r has on the lie temperature of the orchard atmosphere on a frosty night Purple vetch n a heavy volunteer crop of Broad road BroadWindsor BroadWindsor Windsor horse beans and many high weeds were Included In tl the lie e cover crop cropIn In these experiments The conclusions reached were that while the covet cover crop Increased the frost hazard very Iery slightly the differ difference ence made In hi the temperature was not su such as to damage the fruit seriously At Ata a height of five feet above e the I ground 1 the air all temperature was depressed depressed de tie- deI I pressed by the presence of at atthe the cover crop only 01 d degree glee Fahrenheit and 1 degree Fahrenheit at a a height of 10 Inches Since there Is usually but little fruit near the ground these slight differences should have have little effect on the he damage to fruit In n many cases Increased Ed damage g I Ig is probably due to the fact that the grove Is on lower ground where the temperature temperature temper temper- is naturally lower Differences in the amount of damage between clean cu cultivated groves and those In cover crops may also be attributed to some other Influence than temperature tempera tempera- hire ture such as decreased igor vigor of of the tree due to competition from the cover crop a less dormant condition of the or-the the trees caused by more frequent Irrigations Irrigations irrigations or increased deposit of moisture on the lie fruit or foliage from dew dewar or frost The cover crop also acts as a windbreak allowing the cold air to ac accumulate near near the ground and preventing pre venting renting it from mixing with the warmer air ar above |