RbivATion of Weather to Crops 83 



a given point by heating early than it is to raise the temperature 

 after it has once fallen. Trees for home use should be planted in a 

 protected place near buildings or other trees. The Eureka is the 

 best market variety, but Villa Franca, Lisbon, and vSicily are good 

 producers. 



EETTucE 



Head lettuce is destined to become a commercial truck crop 

 in Southern Arizona. It thrives in an arid climate if plenty of 

 irrigating water is available. The quality of the crop can not be 

 surpassed when the right variety is grown. 



The growing conditions necessary for the production of lettuce 

 are a cool growing season, ranging from not over 85° F. to not less 

 than 20°; a rich, easily worked soil which will promote rapid growth; 

 early thinning of the^ plants; frequent cultivation; and adequate 

 irrigation, especially in warm weather. 



In the southern part of the State seed should be sown in plad^ 

 any time from September to January. The plants should be 

 thinned to 12 inches as soon as they have three or four leaves 

 Delay in this checks the growth and increases the cost of the work. In 

 cultivation, care should be exercised not to throw soil into the heads. 

 A sandy soil is objectionable because the sand blows into the heads 

 Head lettuce can be had in the subtropical portions of the State 

 from Thanksgiving until April. In cooler locations it is grown as 

 an early spring crop. Hot weather causes lettuce to stop growing, 

 become bitter, and send up a seed stalk. 



The varieties which succeed best are those with the crinkled 

 leaves. New York or Los Angeles, Iceberg and Denver Market 

 are of this type, named in the order of their popularity. The 

 smooth-leaved lettuces, Hke Big Boston, Tennis Ball, Salamander, 

 etc., are so much inferior in this climate to the other varieties named 

 that it is not advisable to grow them. Cos or Romaine lettuce 

 and varieties of loose-leaf lettuce also grow well, but are not 

 to be compared with either New York or Iceberg. 



I.OQUATS 



Loquats are easily grown in the valleys in the southern parts 

 of the State, below altitudes of 2500 feet. They bloom from No- 

 vember to January and, ordinarily, the flowers are killed by frost. 



