Four orchard floor management strategies—disking, mowing, chemical mow, and clean culture using h... more Four orchard floor management strategies—disking, mowing, chemical mow, and clean culture using herbicides—were evaluated in a `Limoneira 8A Lisbon' lemon orchard in Southern Arizona, starting in the fall of 1993. Disking was the cultural practice used to manage the orchard floor before the start of the experiment. Although disking the orchard floor may have injured shallow tree roots, it provided satisfactory weed control except underneath the tree canopies where bermudagrass, purple nutsedge, and other weed species survived. Chemical mowing with Roundup at 1.168 L/ha did not provide satisfactory control of many weed species and required too many applications to be commercially feasible. This treatment was converted to a combination clean culture and disk treatment (clean and disk) in Summer 1995. Mowing the orchard suppressed broadleaf weed species, allowing the spread and establishment of grasses, primarily bermudagrass, and to a lesser extent, southern sandburr. A fall appli...
Blueberry reducers in Texas must often irrigate with sodic water. Excess Na+ leads to reduced gro... more Blueberry reducers in Texas must often irrigate with sodic water. Excess Na+ leads to reduced growth, necrosis, and plant mortality. Ca2+ is known to ameliorate such detrimental effects in many crops, but little is known about the response of rabbiteye blueberry. To elucidate the influence of Ca2+ on the uptake and translocation of Na+, plants were subjected to NaCl in hydroponics solutions (10, 25, 50 and 100 mM NaCl) and the uptake of Na+ was traced over a 24h period using 22Na+ Additionally, for each treatment, half the plants were supplied with 10 mM Ca2+. Plants were then transferred to identical, but unlabeled, solution, then harvested at intervals up to 28 days following cessation of labelling.Preliminary results indicate that plants subjected to 25 mM Na+ and 0 mM Ca2+ showed less ability to exclude Na+ from the roots, and accumulated more Na+ in roots, stems, an leaves than did plants supplied with 25 mM Na+ and 10 mM Ca2+. Leaf tissue accumulated more Na per gram fresh wei...
Nut count (NC), trunk circumference (TC), competition factor (CF), days from budbreak (DAY), and ... more Nut count (NC), trunk circumference (TC), competition factor (CF), days from budbreak (DAY), and high or low crop year (YR) data were collected on 40 trees at three sites across Texas in 1985 and 1986, to create a model that would predict pecan [Carya illinoensis (Wangenh.) C. Koch] yield. The model developed predicted the natural logarithm of the total nuts on the tree [In(NUTS)]: In(NUTS) = 2.112 + [0.634 × In(NC)] + (0.00119 × TC) – (0.0701 × In(CF)) + (0.00639 × DAY) + (0.728 × YR). The equation accounts for 87% of the variation in yield. The model is not sufficiently accurate to predict individual tree yields well, but additional data show an ability to accurately predict average tree yields.
Several orchard floor management strategies were evaluated beginning in Fall 1993 in a `Limoneira... more Several orchard floor management strategies were evaluated beginning in Fall 1993 in a `Limoneira 8A Lisbon' lemon (Citrus limon) grove on the Yuma Mesa in Yuma, Ariz. and in a `Valencia' orange (Citrus sinensis) grove at the University of Arizona Citrus Agricultural Center, Waddell, Ariz. At Yuma, disking provided acceptable weed control except underneath the tree canopies where bermudagrass (Cynodon dactylon), purple nutsedge (Cyperus rotundus), and other weed species survived. Mowing the orchard floor suppressed broadleaf weed species allowing the spread of grasses, primarily bermudagrass. Preemergence (norflurazon and oryzalin) and postemergence (glyphosate and sethoxydim) herbicides were used to control weeds in the clean culture treatment in Yuma. After three harvest seasons (1994-95 through 1996-97), the cumulative yield of the clean culture treatment was 385 kg (848.8 lb) per tree, which was significantly greater than the 332 kg (731.9 lb) and 320 kg (705.5 lb) per t...
A field trial conducted at Yuma, Ariz., examined the effect of foliar boron application on fruit ... more A field trial conducted at Yuma, Ariz., examined the effect of foliar boron application on fruit yield and quality of Citrus sinensis cv. Hamlin. Boron was applied to 5-year-old trees at five treatment levels (0, 500, 1000, 2000, and 3000 ppm) before or after flowering in a split plot design. At harvest, fruit number, size and quality were determined. Yield (P = 0.01) and average fruit number per tree (P = 0.02) were different among treatments. The highest yield was obtained with the 500 ppm treatment. In this first year of the trial there was no difference in average fruit weight, fruit pH, titratable acidity, peel thickness, juice volume, or soluble solid content of fruit between the treatments. Previous studies indicate that boron influenced in vivo and in vitro pollen germination in many crops. Increased fruit yield may have occurred because boron was transported to the flowers where it exerted its influence on increased fruit set through an effect on pollen viability or pollen ...
Growth of young lemon trees (Citrus limon Burm. f.) is extremely vigorous, and is characterized b... more Growth of young lemon trees (Citrus limon Burm. f.) is extremely vigorous, and is characterized by the appearance of highly vigorous upright shoots that originate in the scaffold branches and trunk of the tree. While maturing, these shoots are considered to be in competition for photosynthates with smaller fruit in the spring and with mature fruit in the fall. During 1993 and 1994, we selectively removed these shoots 12, 6, 4, and 1 (1994 only) times per year, with the objective of increasing fruit size. Neither yield nor fruit quality was affected by the pruning treatments during 1993, but pruning trees 12 times per year increased fruit size by 30% compared to unpruned trees. In 1994, lemon trees pruned 4 times per year had 50% less cull fruit than unpruned trees, and 22% more fruit of size 140 or larger. However, >99% of the flowers and small fruit on trees pruned 4 times per year were aborted, compared with 95% abortion on the unpruned trees. Trees pruned 4 times per year also...
Five rootstocks, `Carrizo' citrange, Citrus macrophylla, Rough lemon, `Swingle' citrumelo... more Five rootstocks, `Carrizo' citrange, Citrus macrophylla, Rough lemon, `Swingle' citrumelo, and Citrus volkameriana, were selected for evaluation using `Limoneira 8A Lisbon' as the scion. Four years of yield and fruit packout data indicate that trees on C. volkameriana and C. macrophylla are superior to those on other rootstocks in growth and yield. `Swingle' and `Carrizo' are performing poorly, and Rough lemon is intermediate. In a similar trial, four `Lisbon' lemon selections, `Frost Nucellar', `Corona Foothills', `Limoneira 8A', and `Prior' selections of Lisbon lemon were selected for evaluation on Citrus volkameriana rootstock. Four years of yield and packout data indicate that the `Limoneira 8A Lisbon' selection has generally outperformed the other selections in both growth and yield, although `Corona Foothills' has been superior in the 1998-99 harvest season.
Arizona lemon producers are often concerned with poor flowering, fruit set and fruit sizing, espe... more Arizona lemon producers are often concerned with poor flowering, fruit set and fruit sizing, especially following excessively warm winter or spring weather. `Limoneira 8A Lisbon' (Citrus limon Burm.) lemons were girdled over a 3-year period to determine if girdling would improve yield or fruit size. Eight trees were girdled each month, from November through August, using a double spiral girdle and a 4.8-mm wide girdling knife. Fruit size measurements were taken throughout the growing season. Trees were harvested individually, and yield; fruit packout and fruit quality measurements were collected. For the 1995/96 harvest, trees girdled in March and May had greater early size and greater yields. Fruit quality was improved as well. For 1996/97 harvest year, trees girdled the previous November and December had significantly greater yield and fruit size. For trees harvested in 1997/98, no treatment was significantly better than the non-girdled trees. The effects of girdling on the or...
Two lemon [Citrus limon (L.) Burm.] cultivar selection trials are being conducted at the Yuma Mes... more Two lemon [Citrus limon (L.) Burm.] cultivar selection trials are being conducted at the Yuma Mesa Agriculture Center in Somerton, Ariz. Some selections in these trials include: `Allen Eureka', `Berna', `Cook Eureka', `Cascade Eureka', `Cavers Lisbon', `Strong Lisbon', `Femminello Comune', `Lapithkiotiki', `Limoneira 8A Lisbon', `Limonero Fino…
Arizona Farm Safety Day has been held annually since 2000 as an attempt to educate students and f... more Arizona Farm Safety Day has been held annually since 2000 as an attempt to educate students and farm workers (pesticide applicators, tractor and equipment operators, irrigators, and field workers) in farm safety. Our programs have emphasized tractor safety, pesticide safety, ATV safety, electrical safety, and firearms safety. The all-day events have been held in Yuma and in Safford, Ariz., and most of the attendees are high school students. Agriculture students from six to eight high schools typically participate. The agenda is determined by consulting with local agriculture leaders. Attendees have the opportunity to attend a 4-hour training session in the morning. Subjects taught at these sessions might include reading a pesticide label, sprayer calibration, wearing proper protection, avoiding spray drift, tractor safety, and farm safety. At least one of these sessions is an outdoors “hands-on” session. Individual participants receive up-to-date information and literature, a certif...
... Some trees can produce 100 kg of fruit (Paulsen, 2005) Once harvested, 'Medjool&... more ... Some trees can produce 100 kg of fruit (Paulsen, 2005) Once harvested, 'Medjool' dates are dried to 24 to 28% moisture content, rather than dried on the tree as are the 'Deglet Noor' dates. ... Paulsen, ME 2005. The amazing story of the fabulous 'Medjool' date. ...
Four orchard floor management strategies—disking, mowing, chemical mow, and clean culture using h... more Four orchard floor management strategies—disking, mowing, chemical mow, and clean culture using herbicides—were evaluated in a `Limoneira 8A Lisbon' lemon orchard in Southern Arizona, starting in the fall of 1993. Disking was the cultural practice used to manage the orchard floor before the start of the experiment. Although disking the orchard floor may have injured shallow tree roots, it provided satisfactory weed control except underneath the tree canopies where bermudagrass, purple nutsedge, and other weed species survived. Chemical mowing with Roundup at 1.168 L/ha did not provide satisfactory control of many weed species and required too many applications to be commercially feasible. This treatment was converted to a combination clean culture and disk treatment (clean and disk) in Summer 1995. Mowing the orchard suppressed broadleaf weed species, allowing the spread and establishment of grasses, primarily bermudagrass, and to a lesser extent, southern sandburr. A fall appli...
Blueberry reducers in Texas must often irrigate with sodic water. Excess Na+ leads to reduced gro... more Blueberry reducers in Texas must often irrigate with sodic water. Excess Na+ leads to reduced growth, necrosis, and plant mortality. Ca2+ is known to ameliorate such detrimental effects in many crops, but little is known about the response of rabbiteye blueberry. To elucidate the influence of Ca2+ on the uptake and translocation of Na+, plants were subjected to NaCl in hydroponics solutions (10, 25, 50 and 100 mM NaCl) and the uptake of Na+ was traced over a 24h period using 22Na+ Additionally, for each treatment, half the plants were supplied with 10 mM Ca2+. Plants were then transferred to identical, but unlabeled, solution, then harvested at intervals up to 28 days following cessation of labelling.Preliminary results indicate that plants subjected to 25 mM Na+ and 0 mM Ca2+ showed less ability to exclude Na+ from the roots, and accumulated more Na+ in roots, stems, an leaves than did plants supplied with 25 mM Na+ and 10 mM Ca2+. Leaf tissue accumulated more Na per gram fresh wei...
Nut count (NC), trunk circumference (TC), competition factor (CF), days from budbreak (DAY), and ... more Nut count (NC), trunk circumference (TC), competition factor (CF), days from budbreak (DAY), and high or low crop year (YR) data were collected on 40 trees at three sites across Texas in 1985 and 1986, to create a model that would predict pecan [Carya illinoensis (Wangenh.) C. Koch] yield. The model developed predicted the natural logarithm of the total nuts on the tree [In(NUTS)]: In(NUTS) = 2.112 + [0.634 × In(NC)] + (0.00119 × TC) – (0.0701 × In(CF)) + (0.00639 × DAY) + (0.728 × YR). The equation accounts for 87% of the variation in yield. The model is not sufficiently accurate to predict individual tree yields well, but additional data show an ability to accurately predict average tree yields.
Several orchard floor management strategies were evaluated beginning in Fall 1993 in a `Limoneira... more Several orchard floor management strategies were evaluated beginning in Fall 1993 in a `Limoneira 8A Lisbon' lemon (Citrus limon) grove on the Yuma Mesa in Yuma, Ariz. and in a `Valencia' orange (Citrus sinensis) grove at the University of Arizona Citrus Agricultural Center, Waddell, Ariz. At Yuma, disking provided acceptable weed control except underneath the tree canopies where bermudagrass (Cynodon dactylon), purple nutsedge (Cyperus rotundus), and other weed species survived. Mowing the orchard floor suppressed broadleaf weed species allowing the spread of grasses, primarily bermudagrass. Preemergence (norflurazon and oryzalin) and postemergence (glyphosate and sethoxydim) herbicides were used to control weeds in the clean culture treatment in Yuma. After three harvest seasons (1994-95 through 1996-97), the cumulative yield of the clean culture treatment was 385 kg (848.8 lb) per tree, which was significantly greater than the 332 kg (731.9 lb) and 320 kg (705.5 lb) per t...
A field trial conducted at Yuma, Ariz., examined the effect of foliar boron application on fruit ... more A field trial conducted at Yuma, Ariz., examined the effect of foliar boron application on fruit yield and quality of Citrus sinensis cv. Hamlin. Boron was applied to 5-year-old trees at five treatment levels (0, 500, 1000, 2000, and 3000 ppm) before or after flowering in a split plot design. At harvest, fruit number, size and quality were determined. Yield (P = 0.01) and average fruit number per tree (P = 0.02) were different among treatments. The highest yield was obtained with the 500 ppm treatment. In this first year of the trial there was no difference in average fruit weight, fruit pH, titratable acidity, peel thickness, juice volume, or soluble solid content of fruit between the treatments. Previous studies indicate that boron influenced in vivo and in vitro pollen germination in many crops. Increased fruit yield may have occurred because boron was transported to the flowers where it exerted its influence on increased fruit set through an effect on pollen viability or pollen ...
Growth of young lemon trees (Citrus limon Burm. f.) is extremely vigorous, and is characterized b... more Growth of young lemon trees (Citrus limon Burm. f.) is extremely vigorous, and is characterized by the appearance of highly vigorous upright shoots that originate in the scaffold branches and trunk of the tree. While maturing, these shoots are considered to be in competition for photosynthates with smaller fruit in the spring and with mature fruit in the fall. During 1993 and 1994, we selectively removed these shoots 12, 6, 4, and 1 (1994 only) times per year, with the objective of increasing fruit size. Neither yield nor fruit quality was affected by the pruning treatments during 1993, but pruning trees 12 times per year increased fruit size by 30% compared to unpruned trees. In 1994, lemon trees pruned 4 times per year had 50% less cull fruit than unpruned trees, and 22% more fruit of size 140 or larger. However, >99% of the flowers and small fruit on trees pruned 4 times per year were aborted, compared with 95% abortion on the unpruned trees. Trees pruned 4 times per year also...
Five rootstocks, `Carrizo' citrange, Citrus macrophylla, Rough lemon, `Swingle' citrumelo... more Five rootstocks, `Carrizo' citrange, Citrus macrophylla, Rough lemon, `Swingle' citrumelo, and Citrus volkameriana, were selected for evaluation using `Limoneira 8A Lisbon' as the scion. Four years of yield and fruit packout data indicate that trees on C. volkameriana and C. macrophylla are superior to those on other rootstocks in growth and yield. `Swingle' and `Carrizo' are performing poorly, and Rough lemon is intermediate. In a similar trial, four `Lisbon' lemon selections, `Frost Nucellar', `Corona Foothills', `Limoneira 8A', and `Prior' selections of Lisbon lemon were selected for evaluation on Citrus volkameriana rootstock. Four years of yield and packout data indicate that the `Limoneira 8A Lisbon' selection has generally outperformed the other selections in both growth and yield, although `Corona Foothills' has been superior in the 1998-99 harvest season.
Arizona lemon producers are often concerned with poor flowering, fruit set and fruit sizing, espe... more Arizona lemon producers are often concerned with poor flowering, fruit set and fruit sizing, especially following excessively warm winter or spring weather. `Limoneira 8A Lisbon' (Citrus limon Burm.) lemons were girdled over a 3-year period to determine if girdling would improve yield or fruit size. Eight trees were girdled each month, from November through August, using a double spiral girdle and a 4.8-mm wide girdling knife. Fruit size measurements were taken throughout the growing season. Trees were harvested individually, and yield; fruit packout and fruit quality measurements were collected. For the 1995/96 harvest, trees girdled in March and May had greater early size and greater yields. Fruit quality was improved as well. For 1996/97 harvest year, trees girdled the previous November and December had significantly greater yield and fruit size. For trees harvested in 1997/98, no treatment was significantly better than the non-girdled trees. The effects of girdling on the or...
Two lemon [Citrus limon (L.) Burm.] cultivar selection trials are being conducted at the Yuma Mes... more Two lemon [Citrus limon (L.) Burm.] cultivar selection trials are being conducted at the Yuma Mesa Agriculture Center in Somerton, Ariz. Some selections in these trials include: `Allen Eureka', `Berna', `Cook Eureka', `Cascade Eureka', `Cavers Lisbon', `Strong Lisbon', `Femminello Comune', `Lapithkiotiki', `Limoneira 8A Lisbon', `Limonero Fino…
Arizona Farm Safety Day has been held annually since 2000 as an attempt to educate students and f... more Arizona Farm Safety Day has been held annually since 2000 as an attempt to educate students and farm workers (pesticide applicators, tractor and equipment operators, irrigators, and field workers) in farm safety. Our programs have emphasized tractor safety, pesticide safety, ATV safety, electrical safety, and firearms safety. The all-day events have been held in Yuma and in Safford, Ariz., and most of the attendees are high school students. Agriculture students from six to eight high schools typically participate. The agenda is determined by consulting with local agriculture leaders. Attendees have the opportunity to attend a 4-hour training session in the morning. Subjects taught at these sessions might include reading a pesticide label, sprayer calibration, wearing proper protection, avoiding spray drift, tractor safety, and farm safety. At least one of these sessions is an outdoors “hands-on” session. Individual participants receive up-to-date information and literature, a certif...
... Some trees can produce 100 kg of fruit (Paulsen, 2005) Once harvested, 'Medjool&... more ... Some trees can produce 100 kg of fruit (Paulsen, 2005) Once harvested, 'Medjool' dates are dried to 24 to 28% moisture content, rather than dried on the tree as are the 'Deglet Noor' dates. ... Paulsen, ME 2005. The amazing story of the fabulous 'Medjool' date. ...
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