XI 



Page 



Behavior of older foliage with acute frost action 524 



Deficient greening of younger leaves 526 



Defoliation due to frost 527 



Behavior of beet and cabbage plants in frost 531 



Frost blisters 



532 



Comb-like splitting of the leaves 53, _ 



Heaving of seeds 536 



Internal injuries in young grain 537 



Internal injuries in the grain stalk 539 



Lodging of the stalk 542 



Condition of sterile heads 542 



Phenomena of movement due to frost 547 



Freezing back of older branch tips 553 



Dying of the cherry trees along the Rhine 555 



Branch blight in forest trees 558 



Freezing of the spring growth 559 



Freezing of roots 562 



Frost clefts 566 



Frost blisters 569 



Frost wrinkles 574 



Bark tatters and cork holes 575 



Phenomena of discoloration in trunks and branches 576 



Frost line 579 



Internal splitting of the trunk and branches 581 



Open frost tears 583 



Canker (Carcinoma) 586 



a. Canker of the apple tree 586 



b. Crotch canker in fruit and forest trees 593 



c. Canker on cherry trees 594 



d. Canker (Scab) of the grapevine 596 



e. Canker on Spiraea 598 



f . Canker of the rose 602 



g. Canker of the blackberry 606 



Corresponding features in canker swellings 607 



Blight (Sphacelus) 608 



Aggregations of parenchyma wood 613 



False annual rings, double rings, etc 615 



Experimental production of parenchyma wood by frost action 617 



Theory of the mechanical action of frost 620 



Rupture of the cuticle 623 



Protective measures against frost 624 



a. Snow covering 624 



b. Use of water 626 



c. Effect of wind 627 



d. Smudge 628 



Frost prediction ^ 630 



Hardy fruit varieties 631 



Snow pressure, ice coating and icicles 634 



Chapter XII. Excess of heat 638 



Death from heat 638 



Poor development of our vegetables in the tropics 639 



Postponement of the usual seed time in our latitudes 639 



Sunburn of leaves in nature 641 



Sunburn spots in conservatories 643 



Defoliation 644 



Sunburn in blossoms and fruits 645 



Injury to grapes from sunburn 646 



Sun cracks .' 647 



Influence of too great soil heat 648 



Failure of the pineapple 650 



Classiness of orchids 651 



Failure in forcing blossom bulbs 651 



Seed which has suffered from self -heating .652 



Chapter XIII. Lack of light 654 



Etiolation 654 



Shading 657 



