High Quality Citrus Rootstock Cleopatra Mandarin, Troyer Citrange Rootstocks Produce Quick-Decline Tolerant Trees Bearing High-Quality Fruit

High Quality Citrus Rootstock Cleopatra Mandarin, Troyer Citrange rootstocks produce quick-decline tolerant trees bearing high-quality fruit

L. D. Batchelor and W. P. Bitters

Cleopatra mandarin and Troyer cit- Rough lemon rootstocks are compared in range are promising rootstocks for or- the bottom table on page 4. ange trees. They are resistant to damage Trees on Cleopatra mandarin rootstock from quick decline and they produce high produced essentially the same amount of quality fruit. fruit as those on the other rootstocks. The Until recently, approximately 95% of yield differences of 10% to 15% were the rootstocks used for orange trees in within the realm of casual error of such California have consisted of sweet or- field experiments. The only real differ- ange, sour orange, and Rough lemon. ence may be the lower yield of Eureka Quick decline made sour orange stock lemon on sour orange roots. Trees on obsolete. The demand for Valencias for Cleopatra rootstock were usually smaller processing purposes made the Rough than those on sweet orange and a little lemon rootstock obsolete as fruit pro- later in coming into full bearing; thus duced on it is lower in juice content and at least 10% more trees could be planted soluble solids than that produced on sour per acre. This would probably make the and sweet orange rootstock. yields per acre about the same, with such Cleopatra Mandarin and Troyer cit- tops as Valencias, as those on sweet or- range rootstocks are more resistant to ange rootstocks. The higher yields of the gummosis than sweet orange stocks, and Marsh grapefruit trees on Cleopatra roots the Troyer is remarkably vigorous as a were probably due to chance. replant in old citrus orchard soil. The trees on Cleopatra stock produced oranges, grapefruit, and lemons of as Fruit, reds, and foliago of the high quality as trees on sweet orange or Cloopatra mandarin. Cleopatra Mandarin sour orange roots. In all cases, the fruit Experimental orchards using Cleopa- was vastly superior to that produced by trees on this root have been longer-lived tra mandarin rootstock budded to Wash- trees on Rough lemon. and more productive as mature trees than ington Navel orange, Valencia orange, One characteristic which makes Cleo- those on any other stock which is as re- Satsuma orange, Marsh grapefruit, Eu- patra desirable for oranges or grapefruit sistant to gum disease. reka lemon, and Lisbon lemon were in California is its proved tolerance to planted at Riverside in 1927 and 1928. the quick decline virus. It also has a This rootstock proved to be better than greater resistance to gum disease than Troyer Citrange average with all these tops. sweet orange or Rough lemon and is as The Troyer citrange is a hybrid of a Average fruit yields, size, and quality resistant as some of the sour oranges. navel orange crossed with pollen of the of fruit of trees propagated on Cleopatra It is as valuable a rootstock for lemon trifoliate orange. mandarin, sweet orange, sour orange, or trees as for oranges or grapefruit. Lemon Continued on next page

Three seven-year old Valencia orange trees planted on old citrus land without soil fumigation. Left, on Troyer citrange rootstock; center, on sweet orange rootstock; right, on sour orange rootstock. ROOTSTOCKS seven years old, the differences in size for general replanting in old citrus soils. are still greater. The trees on Troyer cit- However, the seed supply of Troyer cit- Continued from preceding page range have considerably more fruit-bear- range- is limited. The first trees on this rootstock were ingarea and are already producing more L. D. Batchelor is Horticulturist, liniivrsity planted at Riverside in 1944, on land not Oranges and larger fruit sizes than trees OJ Calilornia College oj Agriculture, Rioerside. on sweet or sour orange rootstocks. previously used for citrus. Campbell Va- W. P. Bitters is Associate Horticulturist, lencia trees budded on Troyer and on the From these data and Obser- University of California College of Agriculture, Seville variety of sour orange were vations it is apparent that the Troyer Riverside. planted for comparison. Trees on both citrange is worthy of commercial trial, The above progress report is based on Re- these stocks budded to Washington Navel especially as replants in old orchards or search Project NO. 193C. and to Lisbon and Eureka lemons were also planted at the same time. Comparison of Fruit Yield, Size, and Quality of Valencia Orange on Sweet Orange, In 1945, additional plantings were Sour Orange, and Troyer Citrange Rootstocks, Planted in 1945 on made on old orchard land with Campbell land Previously Used for Citrus Trees. Valencia trees on Troyer citrange and Morton citrange. Other Valencias were No. planted on sour orange, sweet orange, trees grapefruit, Rough lemon, King man- darin, and Sampson tangelo rootstocks. The Campbell Valencia trees on Troyer 10 Indian orchard sweet orange. 60 92 32 10.22 1.17 citrange rootstock have consistently 10 Keen sour orange...... 70 105 28 10.47 1.21 grown more vigorously than those on 10 Troyer citrange ...... 120 130 58 10.65 1.17 any other rootstock in both the 1944 and 1945 plantings. This rapid growth has also been correlated with greater produc- Comparison of Fruit Yield, Size, and Quality of Valencia Orange on Seville Sour tion even as young trees. Orange, and Troyer Citrange Rootstocks, Planted on Virgin Land, 1944. In the 1944 planting, fruits from the Averoge Percentage Fruit quaiit trees on Troyer citrange are slightly annual of fruit (moturiy 5d2) yield per six. 252 or larger than those from trees on sour or- No. Rootstock tree lor or or Total trees (pounds) P0Cf.d LX soluble l0o:pdl ange rootstocks. A typical eight-year-old roiids tree on Troyer is larger than a tree of l9SO 1951 1952 1950' 1951' 19522 (oer cent) (per 'On*) the same age on sour orange. The growth of the Monroe Lisbon 20 Seville sour orange.. 34 28 66 81 94 35 11.20 1.44 17 Troyer citrange 46 lemon trees on Troyer citrange has been .... 58 87 87 98 30 11.20 1.39 essentially equal or slightly larger than I Large grab sample sixad by hand. the sour orange rootstock trees. . ? Entire merchantable crop rixed in packing house. The Troyer citrange is worthy of limited use as a rootstock for Lisbon Comparison of Fruit Yield, Size, and Quality of Four Citrus Varieties on Sweet lemon. This combination should be used Orange, Sour Orange, Rough Lemon, and Cleopatra Mandarin Rootstocks. in a limited way for trees to be planted Average Percentage of Fruit quality? on old citrus orchard land. More trials fruit size 252 Rootstock y~~~$rorpacked larger box per solubleTotal lot01 are required for the use of Eureka lemon (&& (three-year solid8 ocid trees on Troyer citrange. averoge) (per cent) (per cent) Trees planted in 1945 on old citrus WASHiNGTON NAVEL ORANGE land followed, in most cases, the removal of trees killed by quick decline. The soil Koethen sweet orange ...... 144 44 13.6 0.90 was not fumigated, and the replant trees Brazilian sour orange ...... 171 64 13.2 0.90 were planted right were the old trees had Rough lemon ...... 164 51 11.8 0.70 been without any special precaution. It Cleopatra mandarin ...... 141 46 13.4 1 .oo was evident that the average growth of the trees on Troyer citrange was more VALENCIA ORANGE vigorous than any of the commonly used Koethen sweet orange...... 205 38 13.5 0.85 rootstocks tried. including Rough lemon, Brazilian sour orange ...... 191 50 I 13.1 0.85 grapefruit. Sampson tangelo, sweet or- Rough lemon ...... 187 43 12.1 0.62 ange and others. Cleopatra mandarin ...... 184 45 13.8 0.86 Valencia orange trees were planted in 1945 on sweet orange. sour orange. and MARSH GRAPEFRUIT Troyer citrange rootstocks in a Fillmore 362 sweet orange ...... 239 11.3 1.89 ranch, on land previously used for citrus Brazilian sour orange ...... 250 11.2 1.87 trees. The trees on Troyer stock !ielded Rough lemon ...... 234 9.8 1.65 more, larger. and slightly better quality Cleopatra mandarin ...... 264 10.5 1.83 fruit than trees budded on sweet orange and sour orange roots. EUREKA LEMON By the time the trees in this orchard Bessie sweet orange ...... 285 8.8 5.77 were two years old. the growth and gen- Rubidoux sour orange ...... 222 8.8 5.64 eral vigor of those on Tro>er citrange Rough lemon ...... 277 7.8 5.16 were greater than those of trees on several Cleopatra mandarin ...... 258 8.5 5.71 :elections of sweet orange or sour orange 1 Twenty-yeor average for oranges and grapefruit; 18-year average for lemons. rootstocks. In 19.52, when the trees are 2 Quality dato for oranges and grapefruit rekcted from typical data.

4 CALIFORNIA AGRICULTURE, SEPTEMBER, 1952