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Monday, July 22, 2013

V Shaped Cross Marks on Tomato

Q. I have 'Vee’ shaped cross marks on my tomatoes (especially from Celebrity tomato) starting from the stem and reaching out and down about 1/4 the side.  I always thought these were from lack of water but we try to give all extra water by letting the hose end flood each for 5-10 minutes at least once a day in addition to drip irrigation at 1am, 3am and 5am for 6 minutes each.

A. I think you either are explaining either “catfacing” or “cracking” of the fruit. This is a surprise since Celebrity is known for its lack of both and was developed with one of its intentions to reduce cracking. Some of this type of prevention is by picking the right variety (Celebrity should be one!) for growing and some is garden management.
Fruit cracking on Caspian Pink heirloom tomato

            Two things I can think of contribute to cracking. Catfacing is a different issue. I gave you a couple of links to look at to determine what  you might have. Cracking can be down the side from the stem or around the circumference of the fruit.

            Two things important in cracking are how well the tomato skin will expand without breaking (cracking) and soil moisture. Try to water in the early moring hours several hours before it gets hot.

            Secondly, cover the soil with a light mulch like straw to help slow down the loss of water from the soil.
Radial cracks on Caspian Pink

            The last thing is something that I think most people neglect. Good soil preparation at the time of planting. If the soil is pretty heavy and not “fluffy” or what we call “crumby” (like bread crumbs kind of crumby or a cake-like texture) the roots of the plant will be forced to grow close to the soil surface.

            If the majority of the roots are close to the surface where water is lost quickly during the heat the plant will go into water stress (drought) very soon after an irrigation. If the soil is prepared well so that it has a “crumby” structure then plant roots are distributed through the soil so that it can take up more water before it becomes water stressed.

            Going from water stress to water abundance leads to expansion of the fruit and can lead to splitting. Having enough foliage covering the fruit can also reduce cracking so good canopy coverage of the fruit is important.
Topdressing with straw mulch

            So make sure you soil is well prepared to a depth of at least 12 inches when planting or plant in a raised bed with well prepared soil. Secondly, apply a surface mulch no later than when the fruit begins to set.

            Third, water at the beginning of the day before it gets hot to reduce water stress. Fourth, make sure the plants are healthy and have good foliage covering the fruit. This means the right fertilizer at the time of planting and followup monthly fertilizer applications when you see fruit setting and you are harvesting. These are small applications of fertilizer or lightly foliar feed in the early morning hours.

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